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Co-Sponsored by the Western Plant Health Association
2019 Conference Proceedings
California Plant and Soil
Conference
February 5 & 6, 2019
DoubleTree Hotel & Fresno
Convention Center
2233 Ventura Street
Fresno, CA 93721
Double Tree Hotel & Fresno Convention Center
THANK YOU
TO OUR CONFERENCE SPONSORS!
To download additional copies of the Proceedings or to learn more about the activities of the California Chapter of the American Society of Agronomy,
please visit the website at http://calasa.ucdavis.edu
2019 California Plant and Soil Conference
February 5-6, 2019 DoubleTree Hotel & Fresno Convention Center, 2233 Ventura Street, Fresno, CA 93721
Tel: 559-268-1000. http://calasa.ucdavis.edu
TUESDAY FEBRUARY 5
MAIN SESSION SALON B
California Water Resources: Sustaining Irrigated Agriculture Where Water is Limited
Chairs: Dan Munk & Khaled Bali Speakers will provide unique perspective on the challenge of sustaining irrigated agriculture where water is
limited. They will address impacts of reduced groundwater pumping for agriculture, and opportunities for
increasing water resource production capacity by groundwater banking and increased water use efficiency in
cropping systems. 1.0 CEU CCA Crop Management 1.0 CEU CCA Soil and Water Management
9:30am Dan Munk, CALASA President, Introductory remarks
9:50am Kamyar Guivetchi, California Department of Water Resources
10:20am Ellen Hanak, Center Director and Senior Fellow, Public Policy Institute of CA
10:50am Mark McKean, Kings River Water Association
11:20am Panel Discussion and Q&A (all speakers)
LUNCH- DAY 1 11:45 – 1:30 p.m. (SALON C)
TUESDAY FEBRUARY 5 CONCURRENT SESSIONS: 1:30pm – 3:00 p.m.
SALON B SALON D
Session 1 – Sustainable Water Management:
Recycle, Recharge and Supply Management
Chairs: Sharon Benes, Michelle Leinfelder-
Miles, Florence Cassel Sharma
1.5 CEU CCA Soil-Water Management
Session 2 Climate Smart Agriculture
Chairs: Khaled Bali, Jeff Dahlberg
1.5 CEU CCA Crop Management
1:30 Introductory remarks 1:30 Introductory remarks
1:35 Mark Grismer, UC Davis
Using Recycled Water in Salinas
Agriculture and Salinity Impacts
1:35 Jeff Dahlberg, UC Kearney Agricultural
Research and Extension Center
Climate Change Trends and Impacts on
California Agriculture: Temperature
2:00 Joe Choperena, Project Director,
Sustainable Conservation.
Groundwater Recharge on Farmland:
Challenges and State of the Practice
2:00pm Jennifer Morales, Senior Enviornmental
Scientist, CA Dept. of Water Resources
Climate Change Trends and Impacts on
California Agriculture: Precipitation
2:25 Eric Thorburn, Oakdale Irrigation
District, Modernization & Total
Channel Control Implementation at
Oakdale Irrigation District
2:25pm Richard Snyder, UC Davis Emeritus,
Recalibration of Crop Co-efficients
2:50-
3:00
Q&A/ Discussion (all speakers) 2:50-
3:00
Q&A/ Discussion (all speakers)
BREAK 3:00 – 3:20 p.m FOYER
2019 California Plant and Soil Conference, February 5-6, 2019
TUESDAY FEBRUARY 5 AFTERNOON CONCURRENT SESSIONS: 3:25 – 5:00 p.m.
SALON B SALON D
Session 3 Integrating Technology into
Agricultural Production and Research
Chairs: Mark Lundy and Jeff Dahlberg
0.5 CEU CCA Professional Development
(Bailey)
1.0 CEU CCA Crop Management
Session 4 Irrigation Water Use Efficiency
Chairs: Michelle Lienfelder-Miles, Khaled Bali,
Florence Cassel Sharma
1.0 CCA CEU Professional Development
(Cahn/Norris)
0.5 CCA CEU Soil-Water Management (Bali)
1.0 CEU CURES Nitrogen and IWM
(Cahn/Norris)
3:25 Introductory remarks 3:25 Introductory remarks
3:30pm Dennis Donohue, Director, Western
Growers Center for Innovation and
Technology
Moore’s Law Meets Fresh
3:30pm Michael Cahn, UCCE Monterey
Using the Crop Manage Decision
Support Tool for Improving Irrigation
Efficiency of Coastal Vegetables
3:55pm Jeff Dahlberg, UC Kearney
Agricultural Research and Extension
Center
High Throughput Phenotyping
3:55pm Khaled Bali, UC Kearney Agricultural
Research and Extension Center
Surface Irrigation Automation and
Efficiencies
4:20pm Brian Bailey, UC Davis Dept. of Plant
Sciences
Development of the Next Generation of
Perennial Crop Modeling Tools
4:20pm Greg Norris, State Engineer, USDA-
Natural Resources Conservation Service
Using Simple Graphs to Improve IWM
Effectiveness with NRCS Financial
Assistance
4:45-
5:00pm
Q.A./ Discussion (all speakers) 4:45-
5:00pm
Q.A./ Discussion (all speakers)
5pm POSTER SESSION AND EVENING SOCIAL
SALON A
(beer, wine, soft drinks and hor d’oeuvres)
2019 California Plant and Soil Conference, February 5-6, 2019
WEDNESDAY FEBRUARY 6 CONCURRENT SESSIONS: 8:30 – 10:00 a.m.
SALON D SALON B
Session 5 – IPM: Insect Pests and Disease
Chairs: Rachel Naegele, Jeff Dahlberg, Karen
Lowell
1.5 CCA and PCA CEU Pest Management
Session 6 – Managing Nitrogen Fertilizer Inputs
for Efficiency Chair: Eric Ellison
1.5. CCA CEU Nutrient Management
1.5 CURES N Management
8:30am Introductory remarks 8:30am Introductory remarks
8:35am David Haviland, UCCE Kern
Sugarcane Aphid (SCA)
Identification and Management
8:35am Richard Smith, UCCE Monterey
Fertilizer Use Efficiency in Organic
Vegetable Cropping Systems
9:00am Tom Turini, UCCE Fresno
Plant Resistance Breaking Tomato
Spotted Wilt Virus
9:00am Charles Sanchez, University of Arizona
Perspectives on controlled release
fertilizers for desert vegetable cropping
systems
9:25am Jhalendra Rijal, UCCE
Brown Marmorated Stink Bug in CA
Crops: Pest Identification, Damage
Assessment, and Potential Control
Options
9:25am Hanna Ouaknin, UC Davis, UC Davis Evaluating high-frequency, low-
concentration nitrogen management
strategies to minimize reactive nitrogen
mobilization from California almond
orchards.
9:50-
10:00am
Q.A./ Discussion (all speakers) 9:50-
10:00am
Q.A./ Discussion (all speakers)
BREAK: 10:00 – 10:20 a.m. (Foyer)
CONCURRENT SESSIONS: 10:25 – 12:00 a.m.
SALON D SALON B
Session 7 – IPM: Weeds
Chairs: Jeff Dahlberg, Karen Lowell
1.5 CCA and PCA CEU Pest Management
Session 8 Nutrient Management
Chairs: Daniel Geisseler, Mark Cady
1.5 CCA CEU Nutrient Management
10:25 Introductory remarks 10:25 Introductory remarks
10:30 Kurt Hembree, UCCE Fresno Understanding the Biology of Alkaliweed
(Cressa truxillensis) to Develop Control
Strategies in Pistachios
10:30 Franz Niederholzer, UCCE Colusa
Potassium and Phosphorus Management
in Orchards
10:55 Whitney Brim-DeForest, UCCE
Sutter-Yuba
Weedy Rice Identification and
Management Strategies
10:55 Bob Hutmacher, West Side Research &
Extension Center
How Nutrient Management in Pima
Cotton Differs from Acala Cotton
11:20 Lynn Sosnoskie, UCCE, Merced Weed Ecology: The Biology, Ecology and
Management of Field Bindweed
(Convolvulus arvensis)
11:20 Nicholas Clark, UCCE Kings
Nutrient Management in Forage Crops
11:45 Q.A./ Discussion (all speakers) 11:45 Q.A./ Discussion (all speakers)
CA-ASA BUSINESS AND AWARDS LUNCHEON 12:00 – 1:45 p.m. SALON C
i
Table of Contents
2018-2019 Board Members………………………………………………........…….….……………..….1
Minutes CA-ASA 2018 Business Meeting…………………….……………..……………….…..…..…..2
Past Presidents………………….………………………………..………………………..…….…..……..6
Past Honorees……………………………….…………………………..……………………..……..........7
Honorees Biographies 2019……...……………………………..…..………..………………..………......8
Main Session
California Water Resources: Sustaining Irrigated Agriculture Where Water is Limited…………16
Dan Munk, UCCE Fresno/ 2019 Conference CA Chapter ASA President, Introductory Remarks
Kamyar Guivetchi, California Department of Water Resources
Ellen Hanak, Public Policy Institute
Mark McKean, President of Kings River Water Association
Panel Discussion and Q&A (all speakers)
Session 1. Sustainable Water Management: Recycle, Recharge and Supply Management…………17
Mark Grismer, UC Davis
Using Recycled Water in Salinas Agriculture and Salinity Impacts
Joe Choperena, Project Director, Sustainable Conservation
Groundwater Recharge on Farmland: Challenges and State of the Practice
Eric Thorburn, Oakdale Irrigation District
Modernization & Total Channel Control Implementation at Oakdale Irrigation District
Session 2. Climate Smart Agriculture………………………………........…………………………..…40
Jeff Dahlberg, UC Kearney Agricultural Research and Extension Center
Climate Change Trends and Impacts on California Agriculture: Temperature
Jennifer Morales, California Department of Water Resources
Climate change Trends and Impacts on California Agriculture: Precipitation
Rick Snyder, UC Davis Emeritus
Recalibration of Crop Co-efficients
Session 3. Integrating Technology into Agricultural Production and Research……………….….…47
Dennis Donohue, Director, Western Growers Center for Innovation and Technology
Moore’s Law Meets Fresh
Jeff Dahlberg, UC Kearney Agricultural Research and Extension Center
High Throughput Phenotyping
Brian Bailey, UC Davis Dept. of Plant Sciences
Development of the Next Generation of Perennial Crop Modeling Tools
ii
Session 4 – Irrigation Water Use Efficiency.………………………………………….…………….…54
Michael Cahn, UCCE Monterey County
Using the Crop Manage Decision Support Tool for Improving Irrigation Efficiency of Coastal
Vegetables
Khaled Bali, UC Kearney Research and Extension Center
Surface Irrigation Automation and Efficiencies
Greg Norris, State Engineer, USDA-Natural Resources Conservation Service
Using Simple Graphs to Improve IWM Effectiveness with NRCS Financial Assistance
Session 5 IPM: Insect Pests and Disease……………………………..…………………………………67
David Haviland, UCCE Kern County
Sugarcane Aphid (SCA) Identification and Management
Tom Turini, UCCE Fresno County
Plant Resistance Breaking Tomato Spotted Wilt Virus
Jhalendra Rijal, UCCE
Brown Marmorated Stink Bug in CA Crops: Pest Identification, Damage Assessment, and
Potential Control Options
Session 6 – Managing Nitrogen Fertilizer Inputs for Efficiency………...............................................87
Richard Smith, UCCE Monterey
Fertilizer Use Efficiency in Organic Vegetable Cropping Systems
Charles Sanchez, University of Arizona
Perspectives on Controlled Release Fertilizers for Desert Vegetable Cropping Systems
Hanna Ouaknin, UC Davis, UC Davis
UC Davis Evaluating High-frequency, Low-concentration Nitrogen Management Strategies to
Minimize Reactive Nitrogen Mobilization from California Almond Orchards
Session 7 – IPM:Weeds……………........................................................................................................104
Kurt Hembree, UCCE Fresno County
Understanding the Biology of Alkaliweed (Cressa truxillensis) So Control Strategies Can
be Developed in Pistachios
Whitney Brim-DeForest, UCCE Sutter-Yuba Counties
Weedy Rice Identification and Management Strategies
Lynn Sosnoskie, UCCE Merced County
Weed Ecology: The Biology, Ecology and Management of Field Bindweed (Convolvulus arvensis)
iii
Session 8 – Nutrient Management..........................................................................................................116
Franz Niederholzer, UCCE Colusa, Sutter & Yuba Counties
Potassium and Phosphorus Management in Orchards
Bob Hutmacher, West Side Research and Extension Center
How Nutrient Management in Pima Cotton Differs from Acala Cotton
Nicholas Clark, UCCE Fresno, Tulare & Kings Counties
Nutrient Management in Forage Crops
Poster Abstracts……………………………………………………………………………………...…128
UNDERGRADUATE STUDENT POSTERS……………………………………………………...…129
1. The Effects of Cultivation Practices of Almond on Subsequent Crop in Rotation
Lucio Bahena, Alejandra Gonzalez, Chloe Dugger, Hossein Zakeri
2. Fusarium Falciforme is a Previously Unrecognized Pathogen of Cowpeas, Present in
California
Andrea C. Bourquin, Nick Clark, Cassandra Swett
3. The Effect of Salinity on Nitrogen Acquisition and Biological Nitrogen Fixation
of Alfalfa
Amanda Cox, Chloe Dugger, Hossein Zakeri, Sharon E. Benes, Daniel H. Putnam
4. Potential Use of Remote Sensing in Vineyard Weed Management
Cody Drake, Luca Brillante, Ming-Yi Chou, Anil Shrestha
5. Constraining the Effects of Disturbance Factors on Soil Respiration Efflux
Seth Murick, Garrett Liles
6. The Effects of Water Stress Preconditioning on Heat and Drought Tolerance of Corn in
Northern California
Miriam Pacheco, Amanda Cox, Chloe Dugger, Hossein Zakeri
7. Nitrogen Use Efficiency and Water Use Efficiency of Automated Drip Irrigated Tomatoes
Subjected to Four Fertilizer Rates
Lily Reyes Solorio, Tiffany Frnzyan, Anthony Mele, Florence Cassel Sharma, Dave Goorahoo,
Charles Cochran, and Janet Robles
GRADUATE STUDENT POSTERS—M.S. Candidates……………………………………………136
1. Use of In-season Proximal Sensing Devices to Indicate Corn and Water Deficiency
Taylor Becker, Mark Lundy, Michelle Leinflder-Miles
2. Study of Potential Interactions Between Two Cotton Pathogens, Fusarium oxysporum F.
Sp. Vasinfectum (FOV) and Rhizoctonia solani
Josue Diaz, Robert B. Hutmacher, Margaret L. Ellis
iv
3. Phenotypic and Genotypic Characterization of Fusarium oxysporum F. sp. Vasinfectum
(FOV) isolates as Seedling and Wilt Disease Pathogens of Cotton
Jose Diaz, Robert B. Hutmacher, Mauricio Ulloa, Margaret L. Ellis
4. Lysimetric Determination of Evapotranspiration for Drip Irrigated Onions
Aldo Garcia, Shawn Ashkan, Florence Cassel, Anthony Mele, and Dave Goorahoo
5. Cultivar and Nutrient Management Effects on Nutrient Use Efficiency in Strawberries
Kamille Garcia-Brucher, Charlotte Decock, Kelly Ivors, Gerald Holmes
6. Evaluating Soil Salinity as a Risk Factor for Fusarium Wilt of Tomato
Beth Hellman, Cassandra Swett
7. Water Use Efficiency of Automated ET and Sensor Based Drip Irrigated Broccoli Subjected
to Four Fertilizer Rates
Anthony Mele, Dave Goorahoo, Florence Cassel-Sharma, Aldo Garcia
8. Glutathione Levels as an Indicator of Oxidative Stress in Airjection Irrigated Tomatoes:
Methodology and Preliminary Results
Chaitanya L. Muraka, L. Dejean, D. Goorahoo, F. Cassel S., C. Cochran, A. Garcia, J. Robles
9. The Effects of Midseason Drainage on Greenhouse Gas Emissions and Yield in California
Rice Systems
Henry Perry, Daniela Carrijo, Bruce Linquist
10. Effects of Dormant Drought Stress on Almond (Prunis dulcis) Bloom; or, What if it Doesn’t
Rain in the Winter
Michael Rawls, Ken Shackel, Jong Fei
11. Efficacy Trial of New Dormancy-breaking Treatments in Pistachios
Daniel Y. P. Syverson, Masood Khezri, John Bushoven, Louise Ferguson, Gurreet Brar
12. Interaction of Avg with Varying Nitrogen Application Rates in Relation to Yield and
Quality in Almonds
Travis Woods, Gurreet Brar
GRADUATE STUDENT POSTERS—Ph.D. Candidates……………………………………………148
1. Evaluating Effects of Substrate and Water Use Reduction Potential on Disease Risk in
Containerized Tomatoes
Justine Beaulieu, Bruk Belayneh, Andrew Ristvey, John Lea-Cox, Cassandra Swett
2. A Seat at the Table: California Farmers Speak Up on SGM
Alyssa Jill DeVincentis, Jessica Rudnick, Linda Esteli Mendez Barrientos
3. Nitrogen Dynamics of Organically Fertilized Heirloom Tomatoes
Patricia Lazicki, Margaret Lloyd, Daniel Geisseler
v
PROFESSIONAL (NON-STUDENT) POSTERS…………………………………………………..151
1. Soil and Tissue N Cycling in Corn-Wheat Silage Rotation on Manured Soil
Jorge Angeles, Bob Hutmacher, Till Angermann, Nicholas Clark
2. Cover Crop Cultivar Adaptation to the California Central Valley
Valerie Bullard
3. Effects of Irrigation and Nitrogen Fertilization Regimes on Water Use and Nitrogen Use
Efficiencies in Sorghum and Corn
Florence Cassel, Anthony Mele, Janet Robles, Lily Reyes Solorio, Tiffany Frnzyan, Dave
Goorahoo, Charles Cochran
4. Agronomic Overview of Nitrogen Management Planning Results from the Irrigated Lands
Program
John Dickey, Yohannes Yimam, Tim Hartz, Ken Cassman, Andrea Schmid, Jessica Crichfield
5. Assessment of Orange Irrigation and Fertilization by Combining Grower Operational
Records, Actual Evapotranspiration, Soil and Plant Tissue Data
John Dickey, David Cehrs, Michael Sowers, Ken Cassman, Thomas Harter
6. Working with Commodity Groups, Processors, and Packers to Procure Representative
Crop Samples to Assess Harvest Nitrogen Content
John Dickey, Ken Cassman, Tim Hartz, Daniel Geisseler
7. First Report of a New Stem and Crown Rot Disease of Processing Tomato in California
Caused by Fusasrium falciforme
Erin Helpio, Beth Hellman, Cassandra L. Swett
8. Response of Sorghum and Corn Cultivars to Different Sub-surface Drip and Nitrogen
Fertilizer Applications
Bob Hutmacher, Nick Clark, Steve Wright, Jeff Dahlberg, Jorge Angeles, Rafael Solorio
9. Biofuel Feedstock Production in California Orchards Can Increase Species Richness and
Will Support Pollinator Health Stephen Kaffka, Nic George
10. Yield Progress and Resource Use in Sugarbeet Production in the Imperial Valley of
California
Stephen Kaffka, Ron Tharp
11. Can Biochar Conserve Water in Agricultural Soils?
Sarah E. Light, Claire L. Phillips, Hero Gollany, Thomas Waznek, Kristin M. Trippe
vi
12. Monitoring of Brown Marmorated Stink Bug (BMSB) in Almond and Peach Orchards in
the Northern San Joaquin Valley
Adriana Medina, Tania Herrera, Jhalendra Rijal
13. Rotation Crops as Hidden Hosts of the Fusarium Wilt Pathogen of Tomato, Fusarium
oxysporum F. Sp. lycopersici
Rino Oguchi, Cassandra L. Swett
14. The Effect of Deficit Irrigation on Development of Fusarium Wilt in Tomato
Kelley R. Paugh, Cassandra L. Swett
15. Greenhouse Gas (N2O and CO2) Emissions from High Rate of Woodchip Recycling in an
Almond Orchard
Julio Perez, Diana Camarena, Robert Shenk, Aileen Hendratna, Tom Pflaum, Mae Culumber,
Amisha Poret-Peterson, Brent Holtz, Suduan Gao
16. Quantifying Nitrate Leaching from Central Valley Irrigated Lands with the Soil & Water
Assessment Tool (SWAT)
Yohannes Yimam, George Paul, Tim Hartz, John Dickey, Ken Cassman
Notes………………………………………………………………………………..……………………167
Conference Evaluation Form……………………………………………………………....…………..169
1
2018-2019 Executive and Governing Board Member
California Chapter – American Society of Agronomy
EXECUTIVE BOARD
Past-President
Sharon Benes
Professor
Dept of Plant Science
CA State University Fresno
2415 E. San Ramon Ave, M/S
AS72
Fresno, CA 93740-8033
(559) 278-2255
President
Dan Munk
UCCE Farm Advisor – Fresno
550 E. Shaw Ave. Suite 210B
Fresno, 93710
(559) 241-7521 Office (559)
600-7228
1st Vice President
Karen Lowell
NRCS Agronomist
744A La Guardia
Salinas, CA 93905
831-975-7752 (direct)
2nd Vice President
Eric H. Ellison
Agronomist
Koch Biological Solutions, LLC
Mobile (209) 327-0707 [email protected]
Secretary-Treasurer
Florence Cassel Sharma
Associate Professor
Department of Plant Science
CA State University Fresno
Fresno, CA 93740
(559) 278-7955
GOVERNING BOARD
(Third Year)
Mark Lundy,
UCCE Assistant CE Specialist /
Agronomist
Plant Sciences Department
One Shields Avenue - Univ. CA
Davis
Davis, CA 95616
(530) 902-7295
Rachel Naegele,
Research Scientist
USDA-ARS
9611 S, Riverbend Avenue
Parlier, CA 93648
(559) 596-2823
Steve Vasquez
Director of Agronomy
Sun World, Inc., LLC
559-577-5348
GOVERNING BOARD
(Second Year)
Ehsan Toosi
Senior Scientist-Soil Chemistry
True Organics
(559) 369-2222
Daniel Geisseler
UCCE Associate Specialist,
Dept. of Land, Air & Water
Resources
One Shields Avenue - Univ. CA
Davis
Davis, CA 95616
(530) 754-9637
Michelle Leinfelder-Miles
UCCE Farm Advisor, San
Joaquin Co.
2101 East Earhart Avenue, Suite
200
Stockton, CA 95206
(209) 953-6100 [email protected]
GOVERNING BOARD
(First Year)
Mark Cady
California Department of Food
and
Agriculture (CDFA)
2800 Gateway Oaks Dr.
Sacramento, CA 95833
916-9005217
Jeff Dahlberg
Director and Plant Breeder
UC Kearney Ag Research &
Extension Center
9240 S. Riverbend Ave.
Parlier, CA 93648
559-646-6060 (w)
559-305-3555 (c)
Khaled Bali
Irrigation Water Management
Specialist
UC Kearney Ag Research &
Extension Center
9240 S. Riverbend Ave.
Parlier, CA 93648
2
Board Meeting Agenda
CA Chapter of the American Society of Agronomy (ASA)
Doubletree Hotel & Conference Center, Fresno, CA
February 7, 2018, 12:00 PM – 1:45 PM
1. Call to Order: Sharon Benes, President, California Chapter ASA.
a. Welcomed attendees to the 47th annual Business (Sharon)
b. Award meeting of the California Chapter ASA. The chapter’s annual meeting has
been running since 1972; one of the longest running conferences in California and
one of the few that still prints proceedings.
c. Proceedings available online on the Chapter website (including editions for late
posters abstracts). 1 large pdf. Later parsed, listing individual speakers with
proceedings paper (if submitted) and presentation, pdf format (if authorized).
Will upload pdf’s of presentations to website.
d. Provide the committee with feedback on the evaluation forms (conference,
arrangements, potential future Board members, potential future Honorees)
e. Acknowledgements
i. Student presenters, essay, poster
ii. Student registration, poster boards
iii. Student helpers at registration table
f. Thank you’s:
i. Acknowledged the many sponsors listed in the Proceedings for sponsoring
the session breaks and evening wine/cheese social during the poster
session
- Western Plant Health Assn.—Scholarship Sponsor
- Mid-Valley Ag Services, Valley Tech Analytical Laboratory Services,
Innovative Ag Services, Prime Dirt, Dellavalle Laboratory, FGL
Environ/Agricult. Analytical Services, TerrAvion, ALC Ag Lab &
Consulting, IAP). She also acknowledged Danyal from Dellavalle for
the poster session wine.
ii. Acknowledged that CA ASA is non-profit academic organization and the
meeting attendee registration fees help pay for conference costs. Sharon
thanked all who attended. Those not on mailing list were instructed to
sign pad of paper.
g. Introduced Executive Committee and Governing Board and thanked members for
their hard work for preparing this year’s ASA Plant and Soil Conference. Board
member positions are volunteered positions. She recognized the members plus
3
student help particularly from CSU Fresno for help with registration. 5
students—set up posters. 4 students—registration table.
i. Past President, Bob Hutmacher (Sponsors, Honorees, Preparation Posters)
ii. 1st VP, Dan Putnam (Proceedings, CEU’s)
iii. 2nd VP, Karen Lowell (Conference site arrangements, on-line registration,
some publicity)
iv. Secretary and Treasurer, Eric Ellison (registration, payments)
v. Governing Board
vi. LAST BUT NOT LEAST- Danyal, (DV Lab)—wine, poster session
vii. Kay Hutmacher (and Bob) printing posters one more time!
h. Past Presidents: please stand to be acknowledged
i. Governing Board
Completing 3 years of service and rotating off
1. Margaret Ellis (Fresno State)
2. Dave Holden (Holden Consulting)
3. Andre Biscaro] Exec. Board
Serving 1 year remaining terms:
4. Rachel Naegele,USDA-ARS Parlier
5. Mark Lundy, UCCE
6. Stan Grant, Private Consultant
Serving 2 year remaining term
1. Daniel Geisseler (UC Davis)
2. Michelle Leinfelder- Miles (UCCE)
3. _____________________
j. Member moving onto Executive Board
i. Andre Biscaro moves on to the executive board as Secretary/Treasurer
- Remaining members move up the executive branch
k. Nominations new persons to serve on the CA-ASA Governing Board.
Nominations made by the current board
i. Mark Cady CA Department of Food and Agriculture
ii. Jeff Dahlberg UC Kearney Ag Research & Extension
iii. Khaled Bali UC Kearney Ag Research & Extension
-----------------------------------------------------------------------
iv. Steve Vasquez (Wonderful Citrus). Filling out vacant 1-year term for
Stan
v. Ehsan Toosi (Actagro). Filling out vacant 2-year term for Tom
vi. Motion was made (Nat Dellavalle), seconded (approved) and passed to
approve new members
4
2. Business meeting minutes from the 2017 ASA Plant and Soil Conference (Sharon)
a. Indicated that the minutes of the Feb. 1, 2017 conference were in proceedings
b. Minutes of Feb 1, 2017 Approved
3. Treasurer’s Report (Eric)
a. Eric Ellison present Treasurer’s report for the 2018 meeting and activities.
b. Treasurer’s report was approved.
c. Thanks to Janet Robles, Julie Pedraza, Mala To and Robert Ullo (Fresno State
students) for assistance in running registration both days at the meeting
4. Presentation of awards to 2018 honorees (Sharon)
Presentation of Plaques:
i. Pete Goodell: presenter, Bob Hutmacher
ii. Tim Hartz: presenter, Richard Smith
iii. Jose Faria: presenter, Sharon Benes
5. Student Scholarship Award (WPHA)
a. Eric Ellison (Chair of student scholarship committee).
i. Acknowledgement of other committee members (Maggie Ellis, Bob
Hutmacher) as well the financial support from our sponsor (Western Plant
Health Assoc, $1500).
ii. Discuss the criteria used to judge the students; applicants were asked to
provide 2 letters of recommendation plus a description of work
aspirations. Prompt.
b. Winning essays announced
i. Shannon Mayhew, UC Davis Next Generation Genomics
ii. Jonathan Hubble, California State University, Fresno The Internet of
Things
6. Student Poster Awards (Andre Biscaro)
a. Introduce the committee: Andre (Chair), Daniel Geisseler, Rachel Naegele.
Thank the student volunteers for putting up the poster boards.
b. Undergraduate winners
• Drew Wolter 1st - $400
• Jose Chavez 2nd $200
• Martin Cossio 2nd $200
• Erik Spitzer 3rd $200
c. M.S. Graduate Student winners
• Kenneth Miller 1st $400
• Anthony Mele 1st $400
• Josue Diaz 3rd $200
d. Ph.D. Graduate Student winners
• Deirdre Griffin 1st $400
5
• Umair Gull 2nd $200
• Scott Devine 2nd $300
ended at 1:54 pm
7. Old business and New business
Any items that members were like to present/discuss? None
8. President to pass the gavel (made special for the ASA California Chapter in 1978) to
Dan Munk, incoming President.
9. New President (Dan Munk) presents a plaque and thanks Sharon Benes for her years of
service on the Executive Board.
10. Business meeting adjourned at _1:58 pm_______ hrs.
Attendees reminded to complete conference evaluation forms and return name tag
holders.
Bruce Roberts mentioned the CA-ASA should consider supporting students attending national
competitions.
6
PAST PRESIDENTS
YEAR PRESIDENT YEAR PRESIDENT
1972 Duane S. Mikkelsen 2001 Steve Kaffka
1973 Iver Johnson 2002 Dave Zodolske
1974 Parker E. Pratt 2003 Casey Walsh Cady
1975 Malcolm H. McVickar 2004 Ronald Brase
1975 Oscar E. Lorenz 2005 Bruce Roberts
1976 Donald L. Smith 2006 Will Horwath
1977 R. Merton Love 2007 Ben Nydam
1978 Stephen T. Cockerham 2008 Tom Babb
1979 Roy L. Bronson 2009 Joe Fabry
1980 George R. Hawkes 2010 Larry Schwankl
1981 Harry P. Karle 2011 Mary Bianchi
1982 Carl Spiva 2012 Allan Fulton
1983 Kent Tyler 2013 Dave Goorahoo
1984 Dick Thorup 2014 Steve Grattan
1985 Burl Meek 2015 Richard Smith
1986 G. Stuart Pettygrove 2016 Bob Hutmacher
1987 William L. Hagan 2017 Sharon Benes
1988 Gaylord P. Patten
1989 Nat B. Dellavalle
1990 Carol Frate
1991 Dennis J. Larson
1992 Roland D. Meyer
1993 Albert E. Ludwick
1994 Brock Taylor
1995 Jim Oster
1996 Dennis Westcot
1997 Terry Smith
1998 Shannon Mueller
1999 D. William Rains
2000 Robert Dixon
7
PAST HONOREES
YEAR HONOREE YEAR HONOREE YEAR HONOREE
1973 J. Earl Coke 1996 Henry Voss 2009 Dennis Westcot
1974 W.B. Camp Audy Bell Roland Meyer
1975 Ichiro “Ike”
Kawaguchi
1997 Jolly Batcheller Nat Dellavalle
1976 Malcom H.
McVickar
Hubert B. Cooper,
Jr.
2010 L. Peter
Christensen
Perry R. Stout Joseph Smith D. William Rains
1977 Henry A. Jones 1998 Bill Isom 2011 Blaine Hanson
1978 Warren E.
Schoonover
George Johannessen Gene Maas
1979 R. Earl Storie 1999 Bill Fisher Michael Singer
1980 Bertil A. Krantz Bob Ball 2012 Bob Matchett
1981 R.L. “Lucky”
Luckhardt
Owen Rice Don May
1982 R. Merton Love 2000 Don Grimes Terry Prichard
1983 Paul F. Knowles Claude Phene 2013 Harry Cline
Iver Johnson A.E. “Al” Ludwick Clyde Irion
1984 Hans Jenny 2001 Cal Qualset Charles Krauter
George R. Hawkes James R. Rhoades 2014 Gene Aksland
1985 Albert Ulrich 2002 Emmanuel Epstein Kerry Arroues
1986 Robert M. Hagan Vince Petrucci Stuart Pettygrove
1987 Oscar A. Lorenz Ken Tanji 2015 Bob Beede
1988 Duane S. Mikkelsen 2003 VashekCervinka Carol Frate
1989 Donald Smith Richard Rominger Allan Romander
F. Jack Hills W.A. Williams 2016 Larry Schwankl
1990 Parker F. Pratt 2004 Harry Agamalian Scott Johnson
1991 Francis E. Broadbent Jim Brownell Joe Fabry
Robert D. Whiting Fred Starrh 2017 Ronald J. Brase
Eduardo Apodaca 2005 Wayne Biehler Kenneth
G.Cassman
1992 Robert S. Ayers Mike Reisenauer William L.
Peacock
Richard M. Thorup Charles Schaller Oliberio Cantu
1993 Howard L. Carnahan 2006 John Letey, Jr. 2018 Jose I. Faria
Tom W. Embelton Joseph B. Summers Peter B. Goodell
John Merriam 2007 Norman
McGillivray
Timothy K. Hartz
1994 George V. Ferry William Pruitt 2019 James E. Ayars
John H. Turner J.D. Oster Mary L. Bianchi
James T. Thorup 2008 V.T. Walhood Gene Miyao
1995 Leslie K. Stromberg Vern Marble
Jack Stone Catherine M. Grieve
8
2019
Honorees
Dr. James E. Ayars
Mary Bianchi
Gene Miyao
9
Dr. James E. Ayars – CA-ASA Honoree
USDA-ARS Research Agricultural Engineer
Water Management Research Lab, Parlier CA
Jim Ayars grew up in Penns Grove, New Jersey (the Garden State),
where his interest in agriculture started at an early age. Some of his
earliest memories and work experiences on his uncle’s farm helped
shape the way he looked at problems and solutions. This led him to
pursue an education where he could use engineering principles to
solve problems in agricultural production and efficient use of
natural resources.
After completing a Bachelor’s degree in Agricultural Engineering at
Cornell University, he served in the Air Force at the Little Rock
Arkansas Air Force Base as a Missile Combat Crew Commander. He was in charge of a Titan II
missile station where he spent nearly a year underground. It was in Arkansas that he met his wife
Jeanne. After completing his tour in the Air Force, he was employed by the New York State
Department of Environmental Conservation. A desire to work in international agriculture led him
to complete both M.S. and PhD degrees in Agricultural Engineering at Colorado State University
in Fort Collins. After graduate school Dr. Ayars became an Assistant Professor on the faculty at
the University of Maryland teaching Agricultural Engineering, until USDA-ARS was fortunate
enough to convince him to accept a position and move to the West. In 1980, Jim started his
long-time position as a Research Agricultural Engineer with the USDA Water Management
Research Unit here in the San Joaquin Valley; first at the original Hammer Field terminal
building next to the main Fresno airport, then at the Peach Avenue location and finally at the
new USDA-ARS facility (San Joaquin Valley Agricultural Sciences Center) in Parlier.
Dr. Ayars’ research efforts have been diverse and demonstrate a wide range of capabilities and
interests. As the interest in micro-irrigation expanded during the past three or four decades, Jim
was a key researcher in field testing of drip irrigation practices which ultimately provided
improved management principles for both annual and perennial crops, including the development
of crop coefficients to guide irrigation water needs under microirrigation. Jim’s efforts to
improve our understanding of best practices for drainage water management, the use of saline
irrigation water to meet crop water needs, and impacts of groundwater salinity on crop water use
have been of international interest. In that work, he has utilized small plot research sites, column
and monolith lysimeters, and multiple very large scale on-farm research sites over the years.
These efforts have provided validation and tests of management principles at multiple research
scales and sites that also provided important opportunities to test models of potential use in
management. Complex equipment that Jim and collaborators installed, such as weighing
lysimeters for crop water use research, facilitated not only their research, but also continuing
water management research in the San Joaquin Valley in future years. His research has resulted
in over 200 publications, including several book chapters and a Microirrigation book for which
he served as co-editor.
10
Much of his Jim’s research has been collaborative and it has made good use of the different areas
of expertise of his collaborators. On many projects, Jim has been the driving force in getting the
work initiated, but he also demonstrated appreciation and valued listening to and working with
others to better understand complex field situations and to develop and test useable management
strategies.
In addition to being an honoree of the CA Chapter of the American Society of Agronomy, Dr.
Ayars has received multiple other awards including long-term membership in the Sigma Xi,
Gamma Sigma Delta and Alpha Epsilon Honor Societies in Agriculture and Agricultural
Engineering. He was awarded the Sir Frederick McMaster’s Fellowship by CSIRO in Australia
for support of multiple sabbatical research efforts in South Australia and New South Wales, a
distinguished award associated with some of his multiple and extended research trips serving in
Australia. He has been the recipient of multiple awards for outstanding research papers
(American Society of Civil Engineers, American Society of Agricultural Engineers). Dr. Ayars
also received the USCID Merriam Award for Improved Irrigation in 2014. He recently received
the Royce J. Tipton award from Environmental and Water Resources Institute for the American
Society of Civil Engineers for his work in irrigation and drainage water management.
Over the past 40 years, Dr. Ayars has served the research community and agricultural industry in
a wide range of offices and committee assignments for diverse groups such as the American
Society of Agricultural Engineers, the American Society of Civil Engineers, USCID, USAID, the
UN, and the International Commission on Irrigation and Drainage (ICID). This service has been
in many roles (committee member, chair, planning or organizing committees, program review),
and represented diverse areas of expertise, including drip irrigation, drainage and salinity
management, regional planning for droughts, horticultural crop water use, shallow groundwater
management and regional water use and management decisions. His work has been of national
as well as international interest, and we have been lucky to have him “stationed” here in the San
Joaquin Valley for such a long period of his productive career. Locally, on multiple occasions he
served as the Acting Research Leader of the USDA-ARS Water Management Research Unit in
addition to his duties as a Research Scientist. Jim’s long-term research and education efforts and
those of his many collaborators have served the agricultural community well over the years,
helping define problems, develop options and provide workable solutions for a wide range of
problems. As part of the Carter Peace Initiative in the Middle East he sponsored scientists from
Israel, Jordan, and the Palestinian Authority for a year. Besides his sabbatical leaves in
Australia, he has served on scientific delegations to Jordan and China in addition to his extensive
experience working on a United Nations Development Project in Uzbekistan to improve
irrigation and drainage water management.
Even though Jim had a very active and busy career, he and his wife Jeanne and their daughters,
Amanda and Alicia, also have been generous and active members of their communities, with a
long-time commitment to providing support and care to many people in need of their time and
friendship. This will undoubtedly continue after retirement, but with more time to also enjoy
their children and grandchildren and maybe even some more travel adventures.
11
Mary Bianchi – CA-ASA Honoree
University of California Cooperative Extension
Farm Advisor and County Director
If you see that there’s a need, you just find a way to make it work.
You find the people that are willing to do that with you and it
happens.
You create change one person at a time by listening to what they
have to say and respecting the fact that they are bringing their own
successes, constraints and baggage that you don’t know about.
Mary Bianchi
Mary Bianchi had a long and distinguished career with University
of California Cooperative Extension as a Farm Advisor in San Luis Obispo and the Program
Advisor for the UC Master Gardener Programs in San Luis Obispo and Santa Barbara Counties.
She also served as County Director for UC Cooperative Extension programs in San Luis Obispo
and Santa Barbara Counties.
Mary holds BS and MS degrees in soils and agricultural sciences from Cal Poly San Luis
Obispo. She began a career with the University of California Cooperative Extension in 1984,
serving Santa Cruz, Tulare, Napa and Santa Barbara Counties and at the UC Kearney
Agricultural Center, before transferring to San Luis Obispo County in September 1992 where she
spent 25 years until her retirement in 2017.
Mary’s willingness to tackle whatever needs were most pressing to the community she served
meant that her professional work routinely challenged her to be a lifelong learner, a role she
enthusiastically embraced, and modeled for younger colleagues. Her mantra, “if you can prove it
you can say it”, drove her to a meticulous review of information, and a willingness to say only
what she could confidently support with solid evidence. Her ability to bring together diverse
stakeholders to share information, challenge assumptions and build opportunities for progress led
to tremendous impact in the communities she served. She was routinely invited to speak on a
wide range of topics including water resources management, grapevine nutrition and pest
management, vineyard development, vine pruning and training, citrus and avocado pests and
diseases, walnut pest management, water quality and nonpoint source pollution, field
experimentation and statistical analysis.
Over her years of service Mary won many awards, among them the 2014 Bradford Rominger
Agricultural Sustainability Leadership Award, which honors those who approach major
agricultural challenges with grace, honesty, and a commitment to collaboration across disciplines
and interests. Like the Bradford Rominger award, the CALASA award honors not just
accomplishment, but an ethic of service and broad engagement with the people she serves.
12
Below are a few of the many projects that mark Mary as an outstanding contributor to her
profession and the communities she has served.
During her tenure in San Luis Obispo County, Mary noted the needs of the urban horticulture
community and began coordination of a new Master Gardener Program, with the first class
graduating in June 1996, and assumed the Santa Barbara County Program in 2009. Graduating
hundreds of Master Gardeners during the years of her service, she helped establish an active
membership that staffs phonelines for urban gardening questions, maintains a monthly presence
at five local Farmer’s Markets as well as in local newspapers and offers numerous local
demonstrations and presentations. Even during her retirement, Mary has continued to travel long
distances to present trainings for this group.
In 1999, in response to concerns about water quality impairments in the Monterey Bay National
Marine Sanctuary, Mary developed and directed the 119 team members of the University of
California Farm Water Quality Project, a seven year effort reaching irrigated agriculture
producers with extension education on on-farm water quality planning to manage non-point
source pollutants. This multi-disciplinary, multiagency project reached 2,200 producers in seven
counties and was awarded the 2006 ANR Distinguished Service Award for Outstanding
Teamwork and the 2008 Western Extension Directors Award.
As an extension of the Farm Water Quality Project, in 2008 Mary was a core member of a four
person team that managed a stakeholder analysis of the impacts of food safety concerns on
conservation in the Central Coast region following a foodborne illness outbreak associated with
produce sourced from the region. The project required both careful review of evidence and
extensive discussion among stakeholders and technical experts to evaluate the information within
the context of local conditions. Mary’s ability to manage extensive UC specialist review of the
report built a credible end result, which supported a positive and productive dialogue among
stakeholders both immediately and for the years since. Following this work, Mary saw a need for
more cross-discipline education and created an online learning course to address this need. She
also spearheaded a cross-discipline dialogue with produce buyers, food safety professionals and
conservation professionals to build understanding and balanced management approaches that
protected both food safety and conservation.
When California Department of Pesticide Regulation (DPR) started to require that maintenance
gardeners be licensed if they used pesticides incidentally as part of their work, Mary spearheaded
a DPR funded Pest Management Alliance project in 2010. The project developed a full
Spanish/English curriculum of training that not only focused on providing Integrated Pest
Management (IPM) education for maintenance gardeners, but also reached retailers where the
gardeners purchased the pesticides. This project used peer trainers, and helped reach a largely
unreachable audience. Through Mary’s leadership and vision successes included improved
decisions about pest management by maintenance Gardeners in local landscapes, safer working
conditions, reductions in pesticide use /misuse, and improved business skills for Gardeners. This
project was married to a CA Department of Pesticide Regulation pilot project to increase the
number of Maintenance Gardeners licensed in San Luis Obispo County that Mary also developed
and led.
13
Mary facilitated a community discussion on coexistence measures for conventional, organic, and
genetically modified crops. She recruited a team of UCCE specialists and Advisors to inform
decisions on agricultural water reuse for the Los Osos sewer project. Working with a multi-
disciplinary team in 2010, she created a soil resources planning document for SLO County land-
use decisions by both public and private parties. Other projects focused on drought management
strategies and plant phenology as a tool for landscape pest management.
Throughout her career, Mary was an active member of the Soil Science Society of America, the
American Society for Horticultural Science, the California Avocado Society, and the California
Chapter of the American Society of Agronomy. She served on the governing board of the
CALASA and was President in 2011. Over the course of her career she was a member of the Cal
Poly San Luis Obispo Natural Resources and Environmental Sciences Advisory Council, the
Steering Committee for the UC Statewide Master Gardener Program, and the University of
California Lindcove Citrus Research and Extension Center’s Research Advisory Committee.
During her career she participated in University of California working groups on water
resources, urban horticulture, and subtropical crops.
In her retirement Mary continues to work to improve awareness of the public policy efforts and
products of individual county Advisors, and on the complex interaction of food safety and water
quality public and private regulations on fresh produce production in the United States.
Retirement has allowed Mary to increase her involvement with the San Luis Obispo County
Behavioral Health Board and the Center for Family Strengthening, as well as Friends of
Martha’s Place Children’s Assessment Center – focusing on the development of children ages 0
to 5.
14
Gene Miyao - CA-ASA Honoree
University of California Cooperative Extension, Farm Advisor,
Vegetable Crops, Yolo, Solano and Sacramento counties
Gene Miyao joined UC Cooperative Extension in 1980 as a farm advisor in
Yolo County with commodity responsibility in vegetable crops, sugar beets
and dry beans. In 1990, he accepted a management position with the
California Tomato Research Institute. After a year, he returned to his UC
position, which expanded to include Solano County and later Sacramento
County. He remained in that vegetable crops position for 38 years before
retiring in July 2018. His primary focus has been serving the local
processing tomato industry, especially growers and allied industry, on crop
production issues.
Gene was raised in Clarksburg (near Sacramento) on a small-scale family
farm. He attended UC Davis and graduated with a bachelor’s degree in Agricultural Science and
Management. Concurrently, he also took summer, evening classes at Sacramento City College.
Miyao continued with his studies for a master’s degree in Agricultural Economics from UC Davis,
as well as taking additional post-graduate, college-credit classes in plant pathology, biochemistry
and agricultural marketing. He grew processing tomatoes after college in the upper Delta area. It
was in 1980 that Gene made the tough decision to leave the farm and join UC Cooperative
Extension in a position opened up by the retirement of a respected farm advisor, Mel Zobel.
Miyao is thankful to the many growers, PCA’s, seed company and other industry personnel, as
well as the UC and county colleagues who assisted and cooperated on various projects and
programs over his many years in Cooperative Extension. Within the Yolo office, agronomist Tom
Kearney mentored Gene in experimental plot design, scientific inquiry, crop production and
effective communication. The senior tomato advisors at the time were Don May, Bob Mullen and
Phil Osterli. The statewide specialist for the vegetable crops program was Tim Hartz. Tim’s
insight was invaluable for developing nutrient research programs, as were those of Specialist Kent
Tyler. Weed ecologist Tom Lanini was interested in nightshade control and bindweed
management. His enthusiasm for weed control and fishing were infectious. Gene worked more
closely with plant pathologist Mike Davis to collaborate on research projects than any other
specialist in the UC system. He thanks advisor colleague Brenna Aegerter for her counsel on
programs. The current team of tomato advisors are productive and collaborative. Working in
close proximity to UC Davis, Gene has been fortunate to receive campus assistance from many
individuals—most notably plant pathologists Dennis Hall, Ken Kimble, Bob Gilbertson & his lab
and Frank Zalom, former UC-IPM Director.
In his career, Gene is proud to have helped tomato growers with:
• implementation of integrated pest management (IPM)
• working on a team to narrow the timing and application rate of the herbicide Matrix for
nightshade control
• assisting growers in transitioning from directly field seeding to the use of greenhouse-
grown transplants
15
• leading a team of UC advisors on statewide processing tomato variety evaluations to
identify productive cultivars, including disease resistance
• explored management of many plant diseases including blackmold, Phytophthora root rot,
Fusarium wilt, powdery mildew and several viruses and bacterial pathogens
• cooperating with a team of advisors to demonstrate the value of sulfur dust for powdery
mildew control
• demonstrating the risk of spreading Fusarium wilt from infested stems pieces on
equipment
• modified management of nitrogen
• demonstrating the benefit of supplemental applications of potassium and of phosphorus,
cover crops and composted manure
• participating in sample cost of production studies and updating the economic assumptions
of local farming.
Gene recognizes that his programs were enriched by many summer student workers, some of
whom were members of local farm families, while others remained active in the agricultural
industry.
In retirement, Gene is looking forward to fishing in local waters, hiking, mushroom forays and
some travel adventures with Donna and friends. However, he is still keeping an eye on advances
in agricultural crop production.
16
2019
Main Session
California Water Resources: Sustaining Irrigated Agriculture
Where Water is Limited Speakers will provide unique perspective on the challenge of sustaining irrigated
agriculture where water is limited. They will address impacts of reduced groundwater
pumping for agriculture, and opportunities for increasing water resource production
capacity by groundwater banking and increased water use efficiency in cropping
systems.
Session Speakers:
Kamyar Guivetchi,
California Department of Water Resources
Ellen Hanak,
Public Policy Institute
Mark McKean,
Kings River Water Association
17
2019
Session #1
Sustainable Water Management:
Recycle, Recharge and Supply
Management
Session Chairs:
Sharon Benes
Michelle Leinfelder-Miles
Florence Cassel Sharma
18
Recycled water use, water demand and infrastructure in the
Salinas Valley of California
Mark E. Grismer and Prudentia G. Zikalala
Hydrologic Sciences, UC Davis; One Shields Avenue, Davis, CA 95616
Phone (530) 304-5797, [email protected]
Keywords: recycled water, salinity, groundwater management, vegetables, Salinas Valley
Introduction
Beneficial use of treated or recycled wastewater is increasing in California especially that
used in irrigated agriculture as a means of alleviating demands on freshwater resources and
meeting groundwater sustainability goals. Recycled water use for agricultural production began
some two decades ago in the Salinas Valley of California as part of efforts to limit seawater
intrusion to groundwater aquifers while exploring the possibility of alternative water supplies for
agriculture in the Valley. Concerns remain about rootzone salinity accumulation and salt loading
to groundwater and surface water resources. Meanwhile, at least three other key interacting drivers
affecting water resources availability and quality in the Valley are in play. These include evolving
water agency policies and infrastructure, and grower shift towards greater vegetable/lettuce
production to meet market demands and adoption of more efficient irrigation technologies leading
to greater irrigated acreage across the Valley. Water resources (surface and subsurface)
availability and deterioration, as well as rootzone degradation, remain the major factors limiting
the environmental sustainability of irrigated agriculture in the Valley.
Typically, increased soil salinity occurs during the growing season as crop water demand
leaves irrigation applied salts in the soil followed by winter rains that leach the soil profile salts to
deeper depths. Excess rootzone salinity is managed by adjusting irrigation applications using
leaching requirement concepts that rely on applied water and existing soil salinity (Letey et al.,
2011). Salinity risks increase when using saline water for irrigation and when poor fertilizer and
poor irrigation management are combined. Adoption of more efficient irrigation application
methods alone at the farm-scale may not address the salinization problem of soil rootzones or
subsurface water supplies if there is not an associated decreased total water/salt application at the
regional or Valley scale (Grafton et al., 2018). However, growers may have limited trust in the
agencies promoting particular water policies and tend to doubt that these policies or practices lead
to improved water quality or availability (Drevno, 2018). These trade-offs suggest a need to
develop new irrigation guidelines for adaptation to these changes within the context of sustainable
water use (including groundwater) across the basin.
Surface runoff and leaching are two major transportation pathways for applied salts to
degrade surface and subsurface water resources. Groundwater salinization associated with
leaching and seawater intrusion diminishes groundwater quality in several water supply aquifers
along the California coast (Konikow and Rielly, 1999) and in the Salinas Valley the lower Salinas
River from Gonzales to the estuary is listed (EPA 303d) as impaired for salinity and this salinity
threatens both water supply and sensitive riparian and estuarine ecosystems.
Among several previous actions directed at sustaining groundwater and developing surface
water resources in the Valley, the Monterey County Water Resources Agency (MCWRA) passed
an ordinance in 1995 prohibiting groundwater extraction due to ongoing problems of seawater
19
intrusion into the two major aquifers below Salinas and Castroville. In 1998, Monterey County
Water Recycling Projects (MCWRP) began delivering recycled water (tertiary-treated wastewater)
to 12,000 acres in the northern Salinas Valley. By 2010, the agency had also completed the Salinas
River Diversion Facility enabling greater access to surface water rights and reduced groundwater
pumping. Similar such efforts continue and are largely directed at maintaining the key economic
driver in the Valley.
Irrigated crop production in the Salinas Valley is a valuable output (growing from $2.7 to
$3.6 billion from 1997 to 2017) while the associated saline water drainage and runoff are key
liabilities recognized by water resources managers. Crop values in 2017 alone for leaf lettuce and
berries were $830 and $686 million, respectively (Monterey County Crop Reports, 2017). Here,
we are interested in the interplay between market-driven crop production, adoption of more
efficient irrigation technologies and various water policies and infrastructure adopted or
constructed in the Salinas Valley and their effect on the long-term sustainability of groundwater
resources and rootzone salinity.
Rootzone Monitoring & Modeling
First considering rootzone salinity, a thirteen-year study (2000 to 2012) that included field
monitoring at 8 different sites irrigated with recycled water blends and one control field (irrigated
only with groundwater) was conducted to determine hydrologic factors controlling rootzone soil
salinity and the long-term viability of agricultural production in the region using recycled water
for irrigation. The soil monitoring in commercial cool vegetable (lettuce, cabbage, cauliflower,
broccoli, celery, spinach) and strawberry fields near Castroville in the Salinas Valley enabled
evaluation of the effects of varying levels of treated wastewater irrigation on soil salinity.
Measured average applied water quality (pH, Na, Mg, Cl and K concentrations) delivered to each
site ranged in Electrical Conductivity (ECw) from 0.7 to 1.5 dS/m. Fields were irrigated using
different dilutions of treated wastewater with sprinkler, subsurface drip or furrow systems. Soil-
water salinity in the study area fields increased with increased applied water salinity such that
long-term soil-water salinity was nearly twice that of the applied water. However, growers did not
report yield losses and monitoring results indicated that until applied water Na and Cl
concentrations exceeded 5-6 meq/L, soil-water concentrations remained within an acceptable
lower range. In a geochemical analysis, Vengosh et al. (2002) suggested that roughly 1/3 inches/
yr (3 -10 mm/year) of rootzone seepage associated with agriculture adversely affected the Valley’s
groundwater quality. On the other hand, Platts and Grismer (2014) found that annual winter
rainfall of roughly 10 inches (250 mm) was required to leach accumulated salts associated with
recycled water use from the rootzone in the study area.
Working from the field monitoring study, Zikalala et al. (2018) extended the daily time-
step soil-salinity water and salt balance model developed by Isidoro and Grattan (2011) to predict
long-term (decadal) root-zone salinity, salt loads in drainage and surface runoff waters, and the
annual leaching fraction from fields receiving recycled wastewater in the Valley. Simulation
results showed that the seasonal rootzone salinity remains below stress thresholds for all crops
grown in this region including relatively salt-sensitive crops. Rainfall and applied water EC
predominantly affect the accumulation of salts in the rootzone profile, however, for two sites the
types of crops selected (thus ETc) had a significant effect on soil EC. Minimal profile leaching
occurred with perennial artichoke production, which was also associated with smaller salt loads in
drainage and runoff. Drip and sprinkler irrigation systems resulted in greater plant water uptake
and greater drainage volumes as compared with surface irrigation for similar crop rotations. This
20
is because of how the model accounts for plant-water uptake; that is, frequent irrigations result in
plant-water uptake from the near surface soil layers. This high evapo-concentration in the top soil
layers causes salts to be concentrated at the soil surface resulting in the high salt load with surface
runoff. Annual runoff salt load was an order-of-magnitude greater than drainage salt load. Winter
month rainfall is critical to salt leaching in the Valley and the cyclical reduction in rootzone ECsw
during wet winter months even occurs with variable annual rainfall. The simulations showed that
farms with higher cropping intensity (e.g. 3 crops per year), greater applied water salinity, or
managed with frequent irrigations, have greater salt runoff. While multiple-cropped seasons have
greater plant-water uptake, they concentrate more salts at the soil surface during the growing
season that is then susceptible to removal with rain. Cumulative salt loads as drainage ranged from
0 to 340 lb/ac and those as runoff ranged from 2600 to 7900 lb/ac per decade (Table 1). Of the
primary irrigated crops (artichokes, broccoli, cauliflower, lettuce and strawberries), artichoke
cropping resulted in the least salt loading. The modeling results indicated that potential
salinization of the Salinas River from surface salinity accumulated in field runoff at the end of the
growing season is an important threat from fields irrigated with saline waters, especially for fields
irrigated with drip and/or sprinkler systems. Although irrigation with saline recycled water does
not appear to disrupt soil productivity, accumulation of seasonal salts on the surface later collected
by surface runoff will need to be managed in close coordination with surface water quality goals.
Table 1. Summary of annual average salinity variables for the different field sites.
Site No. 2 3 4 5 6 7
Crop management Vegetables
Vegetables
&
strawberries
Perennial - artichoke
Vegetables
&
strawberries
Vegetables
Irrigation management Sprinkler
or drip
Sprinkler
then drip Sprinkler
Sprinkler
or drip
Sprinkler
then furrow
Sprinkler
then
furrow
% Recycled water 46-92 94-98 58-96 93-100 70-90 90-96
ECW (dS/m) 0.94 1.36 1.06 1.36 1.1 1.37
Root zone ECSW (dS/m) 1.74 2.45 2.4 2.89 1.76 1.95
Root zone ECe (dS/m) 0.13 0.19 0.15 0.18 0.15 0.17
Deep perc. salt load
(lb/ac/yr) 37 184 0 0 137 93
Runoff salt load
(lb/ac/yr) 1247 2341 822 1219 1352 1774
Next, to gain greater insight into the salinization related processes in the Salinas Valley,
Zikalala et al., (2019) analyzed records of surface and ground water salinity along the Salinas River
from the last quarter-century. This analysis provided both greater understanding and perspective
towards managing salinity in arid and semi-arid regions while also enabling determination of the
influence of external climatic variability, and internal drivers in the system. The Valley watershed
covers 4411 mi2 in Monterey and San Luis Obispo counties and a small portion in San Benito
County. The climate is Mediterranean semi-arid with warm, dry summers and cool, moist winters.
Average annual precipitation is 18.5 inches (470 mm) with typical annual variability (±35.6%).
Precipitation generally increases with altitude and decreases from north to south in this closed
basin. They found that rock weathering is the main source of Ca, Mg, Na, HCO3 and SO4 in the
21
river that further enables ion exchange between Ca, Mg and Na. River concentrations of K, NO3
and Cl (salinity) have increased more than expected since 2009 and seem to be associated with
human activities while agricultural practices were the major source of K and NO3. A more direct
anthropogenic positive trend in NO3 that has persisted since the mid-1990s could be associated
with the lag or memory effects of field cropping and use of flood irrigation.
Irrigated Agriculture, Water Policy and Impacts on Groundwater
Hydrologic conditions in the Salinas Valley watershed have evolved dramatically over the
last century as agricultural production first expanded and then shifted from pasture, hay crops and
grazing to intensive vegetable/berry production with the associated increases in groundwater
pumping, river flow regulation (reservoirs) and growing urban areas. Agricultural production and
the urban areas rely on surface and groundwater supplies and because of increasing salinization of
both, the Valley adopted a series of policies or measures directed at improving water availability
and quality while making the most of their available water rights. By 1970, dams were in place
on the upstream tributaries to the Salinas River (Nacimiento and San Antonio Rivers) to
supplement water supply and reservoir releases used to recharge groundwater in the Valley floor
during summer low flows. Adding the Salinas River Diversion Facility in 2010, enabled greater
surface water diversions for agriculture and further efforts to use available water rights are
underway. Here, we explore this development of policies and infrastructure to assess the progress
towards water use sustainability in the Valley and the primary drivers affecting that progress.
Presumably, growers adapt to prevailing crop values by selecting crop systems that yield
the greatest annual net returns. Such incentivization also applies to shifting irrigation technology
in an effort to secure that crop production as needed. Zikalala et al., (2019) developed a multi-
factor model linking trends in crop values and cropping area that affect total irrigated area.
Artichoke, hay, alfalfa and cereal-grain production areas decreased while seasonal vegetables,
berries, wine grapes, orchards and nursery crop areas increased. However, agricultural production
in the Salinas Valley is mediated by the water supply infrastructure required to support irrigation.
In supporting grower water needs, the MCWRA facilitates not only coordination of farmers facing
water problems that arise, but it also facilitates coordination for required infrastructure to service
additional needs in the Valley as outlined in Figure 1 for the past five decades.
Irrigation water use increased along with irrigated crop acreage into the mid-1970s, after
which there is a continued increase in irrigated crop area but an initial decrease in irrigation water
utilized per crop that has since levelled. Applied water use efficiency, or crop water productivity
increased presumably because of adoption of higher-efficiency irrigation technologies, starting
with the shift from surface to sprinkler irrigation methods in 1947 primarily for seed germination
and then later adoption of micro (drip)-irrigation systems in the early 1980’s for vegetable, lettuce
and strawberry production. As first noted in energy economies, Jevon’s paradox suggests that in
a macro-evolutionary model, improvements in efficiency result in the overall increase in scale and
tempo of the system as a whole (Giampietro and Mayumi, 2008). More simply, Grafton et al.,
(2018) found that increased water-use efficiency through adoption of advanced irrigation
technologies does not necessarily increase available water resources in the basin, rather at the
watershed scale that water made available through improved efficiency was reallocated towards
increasing irrigated production areas. Figure 3 illustrates the computed applied water per irrigated
acre (AWIA) for the irrigated area summarized in Figure 2 and the associated groundwater (GW)
pumping required. Note that GW use declined sharply after wells were taken off-line in 1995 and
recycled water deliveries commenced in 1998, and again in 2010 after surface water from the
22
SRDF became available. However, during the following drought period, both AWIA and
groundwater demand increased despite adoption of a broad range of some 14 water conservation
measures, including land-leveling, installation of flowmeters, control of leakage and land
fallowing across 10s to 100s of thousands of acres during the past two decades in the Valley.
Figure 1. Chronology of agricultural water demands, irrigation technology, infrastructure,
institutional and policy initiatives developments in the Salinas Valley.
23
Figure 2. Changes in irrigation technology during past two decades in the Salinas Valley.
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
1993 1998 2003 2008 2013 2018
Age
ncy
Irri
gate
d A
crea
ge
Fur.+Sprinkler
Sprinkler
Drip
Total Irrig.
300,000
350,000
400,000
450,000
500,000
550,000
600,000
28.0
30.0
32.0
34.0
36.0
38.0
40.0
42.0
44.0
46.0
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
200
3
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
Ap
plie
d W
ater
per
Irri
gate
d A
cre
(in
)
AWIA (in)
SWB AWIA (in)
GW as AW (AF)
24
Figure 3. Changes in AWIA computed from measured information (or modeled, SWB AWIA)
and associated groundwater pumping volumes during past two decades in the Salinas Valley.
Further, Zikalala et al., (2019) found degradation trends in ecosystem service indicators
with time across the Valley; including increased salinization of the lower Salinas River, increased
nitrates (NO3) in GW, and declining Fall GW levels (e.g. Figure 4). The ‘Pressure’, ‘Forebay’ and
‘East Side’ aquifers are the primary water supplies for agriculture and urban areas near the upper
end of the Salinas Valley around the Castroville area. Again, note that GW levels recover sharply
by 1998, and again though less so, in 2010-11 after surface-water diversions from SRDF became
available. Analysis of the deeper aquifer GW levels by the newly formed GW Sustainability
Agency found the same response; a ~25 ft GW level recovery in 1997-2000, followed by a gradual
decline during the next decade, then a small GW level recovery in 2010-11 followed by an 8 ft
decline through 2017. Similarly, Figure 5 is a plot of observed residuals from a linearly-fitted
groundwater levels trend model. Positive residuals indicate higher than anticipated observed
variables and negative residuals indicate lower than anticipated observed variables. Drought
periods are shown in grey and letters (Figure 1) indicate the year a water supply or an
environmental policy was enacted. The large negative residuals indicate unsustainable GW
extraction rates after 1972 and again during drought years. Interestingly, increased GW extraction
during droughts continues even though alternative water supply availability increased. Provisions
for alternative sources, including the recycled water project, and surface water only had a short-
term effect on reducing GW extractions. Declining GW levels are not the only challenge for the
Salinas Valley aquifers as increasing estimated area of salinization of the two primary ‘Pressure’
and ‘Forebay’ aquifers also grew during the past four decades (Figure 6). It is likely that GW
salinization will continue as decades of accumulated rootzone salinity reaches aquifer depths in
addition to that caused by declining GW levels and associated sea-water intrusion. The continuing
reliance on groundwater coupled with extreme extractions during drought periods makes the
Valley’s water supply vulnerable to climate shocks particularly to extended droughts.
25
Figure 4. Changes in GW levels of the primary aquifers used for water supplies in the
Salinas Valley.
-80.0
-70.0
-60.0
-50.0
-40.0
-30.0
-20.0
-10.0
0.0
1993 1998 2003 2008 2013 2018
Ave
rage
Fal
l Gro
un
dw
ater
Lev
el b
gs (
ft)
Pressure
East Side
Forebay
Upper Valley
26
Figure 5. Effect of water supply and environmental policy on groundwater extraction in
the Salinas Valley.
Figure 6. Growth in estimated aquifer area (at two depths) of GW salinity expressed as chloride
concentrations at or greater than 500 mg/L during the past four decades.
Accounting for water
The evolving complex feedback between market-driven expansions of crop production as
mitigated by regulations (encouraged adoption of water conservation measures) and greater access
to alternative water supplies (recycled and surface) must be assessed against the measured quality
and availability of the ground- and surface-water resources being managed. Improved water
conservation measures, or increased irrigation efficiency will not of themselves result in an
increase in freshwater available for environmental and other public good services in an
agriculturally-driven basin. In the Salinas Valley, persistent efforts to constrain degradation of
ground- and surface-water supplies in the face of economic pressures associated with vegetable,
lettuce and strawberry production have not been sufficient during the past 2-3 decades to fully
arrest and reverse degradation of these water supplies. As Grafton et al. (2018) suggested, policies
designed to decrease water use in irrigated basins should focus on basin-scale water accounting.
Such a process is underway as part of the Sustainable GW Management Act (SGMA) planning in
the Valley. Table 2 summarizes the attempts at developing water-balance parameters for the
Valley that will require further refinement in the coming decade while additional measures are put
in place to constrain GW extractions or improve GW recharge in the Valley while maintaining an
acceptable level of crop production for economic vitality.
Conclusions
The Salinas Valley is a region that applied technology fixes for agricultural water supply
and demand management as the preferred pathway for water conservation and a means towards
improving chemical and water-use efficiency in the Valley with the hope that such efforts would
-
5,000
10,000
15,000
20,000
25,000
30,000
1975 1985 1995 2005 2015
Esti
mat
ed
aq
uif
er a
rea
wit
h >
50
0 m
g C
l/L
180 ft depth
400 ft depth
27
also reduce water demand and manage runoff water quality from fields. However, there is a need
to evaluate water availability and quality outcomes in vegetable production at the watershed scale.
Irrigation improvements and supplemental water supplies can present unintended consequences
when basin scales and multiple beneficial uses of water are considered. Of concern is the
implementation and expansion of efficient irrigation technologies and expansion of alternative
water supplies without limits to irrigated area expansion that may increase overall production but
leave the basin vulnerable to limited water supplies due to quantity and quality deterioration during
extended droughts. It follows that allocation of water saved through water conservation measures
to new uses can result in “hardening” of water demand; thereby presenting a serious challenge to
water management that meets other human and ecosystem needs especially in a changing climate.
Table 2. Estimated annual Salinas Valley Water Budgets (AF/yr) from 1945, 1995 & 2015 as
part of SGMA Planning in the Valley. Bulletin #52; years
1929-1945 1995 White Paper;
years 1970-1992 St. of Basin 2015; years 1959-2013
Basin Inflows
Salinas River 701,000 547,000 ND
Valley Seepage 239,000 66,000 ND
GW inflows ND 44,000 ND
Totals 940,000 657,000 508,000
Basin Water Use
Agriculture 400,000 ND 464,000
Municipal, Industry & Domestic 15,000 ND 59,000
Totals 415,000 391,000 523,000
Water Outflows to (from) Ocean
River Flows to Ocean 503,000 303,000 -
GW Flows (Intrusion) to Ocean 24,000 (17,000) (11,000-18,000)
Annual Change in Storage (2000) (20,000) (6000)
References
Giampietro, M., & Mayumi, K. 2008. The Jevons Paradox and the myth of Resource Efficiency
Improvement. London, UK: Earthscan.
Grafton, R. Q., Williams, J., Perry, C. J., Molle, F., Ringler, C., Steduto, P., et al. 2018. The
paradox of irrigation efficiency. Science, 361(6404), 748-750,
doi:10.1126/science.aat9314.
Isidoro, D., & Grattan, S. R. 2011. Predicting soil salinity in response to different irrigation
practices, soil types and rainfall scenarios. Irrigation Science, 29(3), 197-211,
doi:10.1007/s00271-010-0223-7.
Konikow, L. F., & Rielly, T. E. 1999. Seawater intrusion in the United States. In J. Bear, A. H. D.
Cheng, S. Sorek, D. Ouazar, & I. Herrera (Eds.), Seawater Intrution in Coastal Aquifers
(pp. 463-506). Netherlands: Sringer.
Platts, B and M.E. Grismer. 2014. Rainfall leaching is critical for long-term use of recycled water
in the Salinas Valley. California Agriculture, 68(3), 75-81, doi:10.3733/ca.v068n03p75.
28
Zikalala, P., Kisekka, I., & Grismer, M.E. 2018. Calibration of a soil salinity model using global
sensitivity analysis and long-term soil salinity assessment for fields irrigated with treated
wastewater in the Salinas Valley, CA. Agriculture – in press.
Zikalala, P., Kisekka, I., & Grismer, M.E. 2019. Hydrologic processing of salinity and nitrate in
the Salinas Valley, CA agricultural watershed. Environ. Monitoring & Assessment – in
press.
29
Groundwater Recharge on Farmland: Challenges and State of the Practice
Sandra Bachand, M.S., M.E., P.E, Principal Engineer, Bachand & Associates
231 G St. Ste. 28, Davis, CA 95616
Phone (530) 574-3375, [email protected]
Philip Bachand, Ph.D. President, Bachand & Associates
231 G St. Ste. 28, Davis, CA 95616
Phone (530) 758-1336, [email protected]
Daniel Mountjoy, Director of Resource Stewardship, Sustainable Conservation
98 Battery Street, San Francisco, CA 94111
Phone (415) 977-0380 ext 303, [email protected]
Ladi Asgill, Senior Agronomist, Sustainable Conservation
201 Needham Street, Modesto, CA 95354
Phone (209) 576-7957, [email protected]
Joe Choperena, Project Director, Sustainable Conservation
98 Battery Street, San Francisco, CA 94111
Phone (415) 977-0380 ext 320, [email protected]
Keywords: Groundwater, recharge, on-farm recharge, climate change adaptation, soil saturation,
soil oxygen, root zone.
Acknowledgements: The findings reported in this presentation are the result of field data
analysis by S.M. Bachand, R. Hossner and P.A.M. Bachand (Bachand & Associates) under
contract with Sustainable Conservation.
Introduction
Agricultural production, population growth, and environmental flow requirements in
California’s Central Valley have outstripped the available supply of surface water which has led
to significant reliance on groundwater. Groundwater pumping over the past 90 years has resulted
in the depletion of 120 million acre feet of groundwater supplies, or three times the volume of all
surface water reservoirs combined. Replenishment of groundwater supplies is now being
recognized as imperative for sustained agricultural production. However, despite concerted efforts
to capture and infiltrate available surface water in some areas of the valley, natural and managed
aquifer recharge has not kept up with the growing demand for groundwater. In addition, climate
change is resulting in higher intensity, less frequent storm events that are producing runoff that
increases the risk of catastrophic flooding of urban and rural landscapes. These peak flood flows
can become a resource for improved groundwater recharge if the flows can be diverted onto
suitable lands for rapid infiltration to the aquifer in ways that simulate the historic floodplain
functions. Farmers, water agencies, and corporate food buyers all recognize the need to expand
recharge to comply with groundwater sustainability regulations, manage flood risk, and to ensure
30
a reliable supply of water to meet the global demand for agricultural products. However, the
science to support rapid expansion of new low-cost recharge projects on private agricultural land
is lagging behind the demand.
Recharge Solutions
We have been evaluating cost effective strategies to expand groundwater recharge during
times of surplus surface water availability and identifying the related barriers to implementation
of these strategies. In addition to the most accepted water agency practices of constructing
dedicated recharge basins and using unlined irrigation canals to increase recharge, farmers have
demonstrated interest in building their own recharge basins and some have shown that significant
amounts of water can be captured and recharged by spreading water on fallow cropland or on
perennial tree and vine crops. On-farm recharge (OFR) projects are quick to implement and are
typically half the cost of building dedicated recharge basins and less than a tenth of the cost of
constructing new surface reservoirs per acre-foot stored. Using farmland to increase recharge also
could ensure sustained productivity in agricultural regions that need to meet their groundwater
replenishment goals. Instead of abandoning cropland to reduce groundwater demand, farmers can
take on the role of replenishing their own groundwater supply.
Comprehensive academic research on the amount of water that can be captured and
recharged on farmland without adversely affecting agronomic health or yields is only beginning,
yet some farmers are already practicing and testing OFR with the hope that they can improve their
own water reliability or earn recharge credits from their Groundwater Sustainability Agencies in
the future.
Monitoring Private Land Recharge
We have been working with water districts and farmers who are voluntarily testing the
concept of OFR on their active croplands since 2011. In 2017, we installed monitoring equipment
on seven OFR monitoring sites in Fresno and San Joaquin Counties. Each location was comprised
of a test plot to receive OFR which was paired with a control plot having the same crop and soil
characteristics, but it received normal irrigation management via flood or drip irrigation systems.
The equipment enabled us to monitor the volume of water recharged, soil infiltration rates, as well
as moisture and oxygen levels in the crop’s root zone to better understand soil characteristics and
potential crop risks when applying extra water to active cropland. We also documented the
grower’s unique recharge methods, associated crop management decisions and yields based on
grower’s self-reported information. Only two of the monitoring sites were able to obtain water for
recharge in 2018, but monitoring has continued at six of the sites throughout the irrigation season
to document baseline conditions for soil moisture and oxygen levels of typical irrigation practices.
In addition to our research monitoring sites, Sustainable Conservation is collaborating with two
irrigation districts that are encouraging OFR and have collected recharge data from growers who
voluntarily applied more surface water than their crop demand. During 2017, 117 growers in
Madera and Tulare Irrigation Districts received water for OFR at 240 fields. District staff tracked
water quantity and timing for each location and provided this data to Sustainable Conservation for
further analysis by crop and soil type and comparison of evapotranspiration rates to determine net
recharge quantities.
31
Results
Throughout 2017, Sustainable Conservation documented a total of 7,330 acre feet of water
recharged on 245 locations totaling 19,931 acres. Crops on these fields included almonds, grapes,
pistachios, cherries, walnuts, peaches, oranges, and alfalfa, and fallow fields typically used for
wheat, corn, and squash. Volume of water recharged per acre varied from just a few inches, by
farmers trying the practice for the first time and mostly interested in the salt leaching benefits, to
over ten feet on a vineyard following harvest. In November 2018, over 18 feet of water was applied
on the monitored vineyard. Analyses of the 2017 monitoring site data indicate:
• Oxygen depletion follows increases in soil saturation but quickly recovers when
application of surface water ceases.
• Oxygen depletion also occurs during normal irrigation events but not to the extent or
duration of recharge events.
• Soil salinity declined slightly in the shallow soil profile following recharge as measured
with volumetric ion content sensors.
Soil oxygen was measured to understand the potential implications of OFR on oxygen levels in
the pore space. Correlation analysis evaluated a variety of local site conditions and management;
it did not provide a simple rule of thumb or algorithm describing the relationship of soil moisture
and soil oxygen depletion. However, from the literature review, analyses, and observations, we are
presenting a conceptual model of drivers of soil oxygen levels, consumption and transport as a
hypothesis.
• Plant and soil microbial respiration consumes soil oxygen. Where and when depends upon
microbial presence, root distribution, time of year, and quite likely the plant type because
some plants have mechanisms to help withstand soil saturation. However, we did not study
the effect of plant type because we didn’t have sufficient data.
• Oxygen is replenished through diffusive transport of oxygen from the surface to soil pores
across and at depth in the root zone. Several factors can limit diffusive transport:
o Surface water can create a barrier preventing diffusion into the soil profile.
o Pore moisture can lead to barriers to pore connectivity and oxygen diffusion across
those pore spaces, limiting replenishment pathways and diffusion rates.
• Reduced oxygen in the pore space provides feedback to the plant, reducing local respiration
rates by the plant.
From this model, farmer recharge management decisions can affect soil oxygen diffusion
temporally and spatially throughout the root zone. Crop types also affect root depth and
distribution, affecting respiration and oxygen consumption throughout the profile.
We realize that some plants are better able to accommodate low oxygen, and even saturated,
conditions. However, based on our study data, we propose the following guidelines to help farmers
implementing an OFR program to minimize conditions that could lead to low soil oxygen levels:
32
• Avoid standing water on a given location of more than 3 to 4 days
• Use past, successful flood irrigation methods for meeting crop needs as reasonable
guidelines for developing an OFR program.
There is clearly a need for more information to provide more detailed guidance and assurance to
growers and water managers. Current efforts led by the California Department of Water Resources
Flood-MAR Research Advisory Committee is encouraging researchers, farmers, and water
agencies to work together to identify priority research, data and decision support tool needs. We
encourage field agronomists to collaborate with each other and through Flood-MAR to identify
critical research needs, compile additional field experience and work collaboratively to conduct
additional field trials.
33
Implementing Total Channel Control ® Technology at
Oakdale Irrigation District
Steve Knell, P.E., General Manager,
Oakdale Irrigation District
1205 East F Street, Oakdale, CA, 95361
Phone (209) 840-5508, [email protected]
Eric Thorburn, P.E., Water Operations Manager/District Engineer
Oakdale Irrigation District
1205 East F Street, Oakdale, CA, 95361
Phone (209) 840-5525, [email protected]
Keywords: Oakdale Irrigation District, Total Channel Control, Rubicon, Water Resources Plan
Introduction
Oakdale Irrigation District (OID) is an 82,000 acre irrigation district located in both the
northeast foothills and valley floor of the San Joaquin Valley of Central California. In 1909, OID
was organized under the Wright Act by a majority of landowners within the district in order to
legally acquire and construct irrigation facilities and distribute irrigation water from the Stanislaus
River.
Figure 1. Location of Oakdale Irrigation District
34
In 1910, OID and the neighboring South San Joaquin Irrigation District (SSJID) purchased
Stanislaus River water rights and some existing conveyance facilities from previous water
companies. Both districts continued to expand their operations over the ensuing decades. Since
their creation, OID and SSJID have constructed dams and reservoirs to regulate surface water
storage and deliveries. Most of these dams were constructed in the 1910s and 1920s, including
Goodwin Dam (1913), Rodden Dam (1915), and Melones Dam (1926), which provided
112,500 acre-feet (ac-ft) of shared capacity. To provide supplemental water storage for OID and
the SSJID, the Tri-Dam Project was created and built in the 1950s. Tri Dam is a 3-dam network
of facilities; Donnells Dam and Beardsley Dam on the Middle Fork of the Stanislaus River, and
Tulloch Dam on the main-stem of the Stanislaus River. Hydroelectric generation was also a part
of these facilities and today Tri Dam power generation is just over 100 MW per year. The power
is sold under contract to Santa Clara Valley Power. In the early 1970s, the Bureau of Reclamation
replaced the Melones Dam with the larger 2.4 million acre-foot New Melones Dam and Reservoir.
The districts have an operations agreement with Reclamation that outlines the operations of that
facility in fulfilment of the district’s senior water rights.
These historic and significant capital investments in water storage projects have led to a
stable, plentiful water supply for OID. However, over the 50 years that followed, OID focused its
financial resources principally on paying off these capital investments and bond debt; as a result,
OID had invested little in replacement, modernization, automation or rehabilitation of its existing
system which caught up to OID in the late 1990s.
Water Resource Planning
Since its formation on November 1, 1909, OID has watched statewide changes as water
progressed from being a local resource, fueling the areas’ mining and agricultural businesses, to a
commodity aggressively sought statewide by municipalities representing millions of people. Wary
of these shifting priorities, OID took it upon itself to develop a Water Resources Plan (WRP), a
plan focused on protecting OID’s water resources over the next 20 years. This two and a half year
effort came to an end with the certification and adoption of the WRP in June of 2007.
Key components and the local benefits to be derived from the WRP included;
1. Protection of OID’s water rights by defining the uses and purposes of OID’s water over the
next 20 years.
2. An infrastructure modernization and replacement program that will involve the expenditure of
$169 million dollars in construction work to replace, rebuild and modernize OID’s water
infrastructure.
3. A financial strategy to pay for these improvements with water sales and transfers. Thus
incurring little or no burden to current customers by way of water rate increases. Keeping
water rates low is OID’s way of providing our farming community a return on their investment.
4. Protection of the groundwater resources serving the City of Oakdale and local businesses and
industries relying on this resource. Good quality drinking water is a priority protection focus
in Oakdale.
5. Securing surface water supplies for the City of Oakdale should such a demand present itself in
the coming years.
35
The WRP’s Overview and Financing
The Preferred Program coming out of the planning process was a roadmap outlining how
OID was to meet the long-term rebuilding and modernization needs of the district. Those needs
and costs include;
1. Main Canal and Tunnel rehabilitation projects totaling ($44,553,000);
2. Canal and lateral rehabilitation ($24,418,000);
3. Flow control and measurement structures ($13,856,000);
4. New and replacement groundwater wells ($10,460,000);
5. Pipeline replacements ($45,366,000);
6. North Side Regulating Reservoir ($6,264,000);
7. Delivery turnout replacements ($4,680,000);
8. Outflow management projects ($10,947,000);
9. Reclamation projects ($5,813,000); and
10. Miscellaneous in-system improvements ($2,386,000).
In 2007 dollars these improvements represent nearly $169 million over a 20-year window. To
finance these improvements the WRP relied on the revenues being derived from water
transfers/sales.
OID now has a 20 year history of marketing conserved water to willing buyers and using that
revenue to finance capital improvements. Those improvements result in more conserved water
which is then sold again through market transfers in order to generate more revenues to meet the
needs of its water delivery system. These efforts have served OID well, generating some $75.3
million in water transfer revenues since 1998. OID has spent all of that money on rebuilding and
modernizing its water infrastructure to the benefit of the agricultural community it serves. It’s a
simple plan that has brought OID to a decision point on its next level of water management control
and conservation, one OID believes can be provided by Rubicon Systems.
The Rubicon Selection for Automation
OID had been a user of the Rubicon FlumeGates™® for a number of years as it worked
its way through various canal gate automation products on the market. The past experience with
Rubicon was a beneficial one, not without growing pains as Rubicon evolved their product line,
but OID saw a product with potential that shortly matured into a low maintenance, user friendly,
accurate flow measurement and gate control.
Total Channel Control® (TCC)
During the initial funding of the WRP it became a focus of OID to replace a majority of its
main canal control gates and lateral headings beginning in 2006 with FlumeGates™ for enhanced
water measurement and control. In 2009, with the progress and success of that program along
with completion of a major regulating reservoir serving farmland on the north side of the Stanislaus
River, OID began looking at enhanced flow control within its laterals. In 2010, as its next tier of
conservation projects, OID and Rubicon Systems America Inc. (Rubicon) embarked on a
demonstration project to bring Network Control Technology to the OID delivery system.
36
The OID system is a 100 year old gravity flow system delivering about 225,000 acre-feet per year
to a mix of irrigated pasture, almonds, walnuts, rice and both small ranchette and large agricultural
field sizes. All these variables lead to difficulty in providing a high level of service and efficient
management of irrigation water. To address these issues with modern technology, the $3 million
Total Channel Control (TCC) Pilot Project was agreed upon by Rubicon and OID. The coordinated
in-house constructed and managed project involved a combination of retrofit or replacement of a
total of 28 check structures and the installation of 31 gates on the 6.5 mile Claribel Lateral and the
8.5 mile Cometa Lateral. The civil works were completed during the winter of 2010/2011 and
progressive implementation occurred during the 2011 water season. The fully implemented
system has been in operation since that time.
The Claribel Lateral TCC System
The Claribel Lateral has a heading capacity of 138 cfs. From its heading-to-spill the canal
is 6.5 miles in length. It contains 18 pools along its reach. The system is mostly earth lined with
sections of concrete lining and sporadic sections of pipeline.
The Claribel Lateral system was chosen to test the ability of TCC in reducing operational
spill. Operational spills are an operating inefficiency of open canal systems but are a necessity to
insure all water orders are fully filled. The amount of losses at the end of the Claribel Lateral
ranged from about 1,500-2,000 acre-feet per year depending on various factors.
Under full implementation of the TCC system from 2012 to 2018, operational spill has
been reduced to an average of 14 acre-feet per season. The spill that has occurred during full
implementation has primarily been a result of drain water entering the lower end of the Claribel
Lateral at times when there was no downstream irrigation demand (i.e. throughout winter oat
harvest and field preparation for corn).
37
Figure 2. Operational Spill Performance on the Claribel Canal as TCC was Implemented
The Cometa Lateral TCC System
The Cometa Lateral has a heading capacity of 306 cfs. From its heading-to-end the canal
is 8.5 miles in length. It contains 13 pools along its reach and is much flatter than the Claribel
System.
The Cometa was chosen in the hopes of improving operational flows to its terminus; the
beginning of the Hirschfeld Lateral serving another water division. The upper Cometa Lateral
flows through and serves another water division of OID and is managed by a different Distribution
System Operator (DSO). As human nature is, the upper operator ensured their needs were filled
and the lower operator was pretty much at their mercy for water; hence a “feast or famine”
situation.
The focus on the Cometa Lateral was to minimize flow fluctuations to the downstream
water division while maintaining consistent water levels for deliveries within its 13 pools. As can
be seen in Figure 3 below, TCC implementation was successful in achieving that result.
Statistically, average water level variations on the Cometa Lateral improved by 92% to be within
+/- 2 inches of the canal’s set points for water deliveries.
38
Figure 3. Water Level on the Cometa Canal after TCC Implementation
TCC Pilot Project Costs
Description Project Costs
Rubicon (Gates, Labor, Software, etc.) $1,535,752
Surveying $46,678
OID Material and Equipment $893,154
OID Design and Construction $706,386
Total $3,181,970
Using these costs and calculating a cost/mile unit rate for the number of systems installed,
the total TCC cost was $212,131 per mile. Assuming a reasonable California water transfer rate
of $125 per acre foot, the payback for the anticipated water saved was about 10 years. For OID,
that is a marketable return.
Results of TCC Implementation
OID implemented TCC on just 2 canals of a much larger system. The results have been a
substantial savings in water and precise flow control to the downstream division, but also an
improved level of service at the farm gate. Grower/farmer responses who experienced TCC were
minimal at best and in the irrigation district business, that is a big plus. There were no complaints
from users, just casual responses on the improved service standard afforded to them. On the
DSO/operator side, those who were exposed were impressed with the ease of functionality. In
39
many cases, what began with intimidation and reluctance from DSOs to have TCC implemented
within their working division has now transitioned to requests for implementation and expansion
of the system in their area. There have been noticeable customer service improvements as a result
of TCC implementation as time that was previously spent making adjustments at each inline drop
structure is now available for monitoring and patrolling around the Division. Other benefits
derived from TCC operation included an increased level of accountability from both DSOs and
constituents with the improved measurement and historical trending, safety associated with no
longer manually operating weirs and slide gates, improved response to last minute requests or
unanticipated water orders/changes as a result of decreased water travel time, and increased
opportunity time for potential groundwater recharge benefits.
TCC Expansion
With a better understanding of the benefits derived from the project and a consistent
operational performance over the last 8 water seasons, OID has begun to expand upon the existing
TCC system as funding becomes available and/or as lifecycle replacement improvement projects
arise. OID staff estimates that TCC implementation on an additional 100 miles of OID’s open
ditch facilities would be beneficial. As civil works continue to be performed to keep up with life
cycle replacement in these potential TCC expansion areas, TCC operational components and
infrastructure design aspects are taken into consideration. Since the TCC Pilot Project an
additional 3 miles of expansion has occurred through lifecycle replacement projects on a total of
10 check structures branching off of the existing TCC system to OID’s Stowell, Brichetto and
Lower Cometa laterals.
In May 2018, OID was also awarded up to $3 million in cost-share funding toward the
Phase 1 TCC System Modernization Project (Phase 1 TCC Project) as part of the Water Use
Efficiency Grants Program under Proposition 1, Water Quality, Supply, and Infrastructure
Improvement Act of 2014. The $6.5 million project is being completed with in-house engineering,
surveying and construction forces and will involve a combination of retrofit or replacement of a
total of 31 check structures and the installation of 46 Flume Gates on 17.5 miles of the Tulloch,
Burnett, Kearney and Hirschfeld Laterals. The Phase I TCC Project is proposed to be completed
over a 3-year period and, in addition to the benefits derived from the TCC Pilot Project, is
anticipated to result in an estimated 4,170 ac-ft of reduced operational spill.
To accommodate future expansion of the TCC system, OID is also in the process of
completing the construction of a new 190’ SCADA radio communications tower on the north side
of the District. Upon completion of the Phase I TCC Project in the spring of 2021, approximately
38 miles of the total 200 miles of OID’s open ditch facilities will be operating in automated
downstream level control using TCC technology. OID continues to be very optimistic about
Rubicon Systems and the TCC technology that has been implemented. The potential for additional
water savings at a marketable rate through TCC implementation fits OID’s water conservation and
marketing prospectus and continues to have great promise for the future.
40
2019
Session #2
Climate Smart Agriculture
Session Chairs:
Khaled Bali
Jeff Dahlberg
41
Climate Change Trends and Impacts on California Agriculture: Temperature
Jeff Dahlberg,
UC-ANR Kearney Agricultural Research and Extension Center,
Parlier, CA 93648,
Tapan Pathak,
UC-ANR Merced,
Merced, CA 95343,
Mahesh Lal Maskey, UC Davis, Dept. of Land, Air and Water Resources,
Davis, CA 95616,
Faith Kearns, UC-ANR CA Institute for Water Resources,
Oakland, CA 94607,
Khaled Bali, UC-ANR Kearney Agricultural Research and Extension Center,
Parlier, CA 93648,
Daniele Zaccaria
UC Davis, Dept. of Land, Air and Water Resources,
Davis, CA 95616,
Introduction
California is a global leader in agriculture and its unique environment supports more than
400 types of commodities. The state supplies over a third of the US’ vegetables and two-thirds of
its fruits and nuts. California is not only highly productive but produces very high-quality
agricultural products. Current and future climate change poses many challenges to the state’s
agricultural sector. We present a synthesis of climate change impacts on California agriculture in
the context of: (1) historic trends and projected changes in temperature, precipitation, snowpack,
heat waves, drought, and flood events; and (2) consequent impacts on crop yields, chill hours,
pests and diseases, and agricultural vulnerability to climate risks.
We highlight a few important findings and directions for future research and
implementation which has been more thoroughly reviewed in Tapan et. al., 2018. The paper
details sufficient evidence that the climate in California has changed significantly and is
expected to continue changing in the future. These changes justify the urgency and importance of
enhancing the adaptive capacity of agriculture to meet these climate change impacts and
42
consequences. Since agriculture in California is so diverse and each crop responds to climate
differently, climate adaptation research should be locally focused along with effective
stakeholder engagement and systematic outreach efforts. This should lead to effective adaptation
and implementation of strategies developed to maintain the productivity and livelihoods of
California farmers.
Method
Tapan et al. (2018) outlined a detailed literature review to document the most current
understanding on California´s climate trends in terms of temperature, precipitation, snowpack,
and extreme events such as heat waves, drought, and flooding, and their relative impacts on the
state’s highly productive and diverse agricultural sector. The review relied on credible sources
such as the most recent reports from Intergovernmental Panel on Climate Change (IPCC),
various state agency reports, and research articles focused on climate change and agriculture in
California. The authors reviewed direct or indirect impacts on California’s agricultural sector. As
an example, both average and extreme temperatures and precipitation patterns influence crop
yields, pests, and the length of the growing season, but extreme events, such as heat waves,
floods, and droughts, may lead to larger production losses, earlier spring arrival, and warmer
winters due to temperature increases that cause increased pressure as result of diseases and pests,
and shrinking amounts of snowpack that lead to greater risks related to water availability for
agriculture. A detailed review of the findings are presented in the authors’ paper.
Some Key Findings
Every region in California is experiencing increased changes in temperature and models
predict that this will continue; however, no clear trends in precipitation were detected. While
statewide temperature trends are consistent with global temperature trends, incremental change
in mean temperatures for California are about 1.2-2.2º F compared to the last century (WRCC,
2013). Month to month, yearly and decade long variability will continue in California for
precipitation and the state will remain vulnerable to drought and flooding cycles.
On the other hand, no clear trends in precipitation were detected. Month to month, yearly
and decade long variability will continue in California for precipitation and the state will remain
vulnerable to drought and flooding cycles. The studies showed annual precipitation records
exhibit significant inter-annual variability, which makes trend analysis for water resource
planning, management, and policymaking very difficult (DWR, 2015a). The physical process
43
driving such observations remains an area for future research.
Figure 1. Annual temperature trends for the 11 climate regions in California between 1918-2016
(Source: Cordero et al. 2011).
Many of the crops in California are sensitive to increases in temperature (Figure 1). Many
vegetable crops will see decreases in yields, while perennial specialty crops could see yield
declines if chilling requirements are not met. Annual crops such as corn, soybeans, rice and
cotton could see decreased yields from failed pollination or boll set. Temperature will also
impact the movement and resilience of many insects, and it is expected that they will move
further north as temperatures increase.
California is a Mediterranean climate and receives much of its rainfall and snow during
the winter months. Approximately 9 million acres of agricultural land in the state are irrigated
and for the most part these high value irrigated crops rely on wet winters to maintain water
availability throughout the dry, warm summer months. Projected snowpack levels could see a
44
loss of 48-64% and an average increase in temperatures in the Sierra Nevada could range from 7-
10º F if emissions do not change. As seen in Figure 2, historical and projected snowpack
scenarios in California under two potential warming conditions hint loses up to 65% by the end
of the century (CA DWR, 2015b).
45
Climate Change Trends and Impacts on California Agriculture: Precipitation
Jennifer Morales
Senior Environmental Scientist
CA Dept. of Water Resources
559-230-3381
46
Recalibration of Crop Coefficients
Richard Snyder
UCCE Davis Biometeorology Specialist (Emeritus)
LAWR/Hoagland
One Shields Avenue
243 Hoagland Hall
Davis, CA 95616
(530) 752-4628
47
2019
Session #3
Integrating Technology into
Agricultural Production and Research
Session Chairs:
Mark Lundy
Jeff Dahlberg
48
Moore’s Law Meets Fresh
Dennis Donohue
Director
Western Growers Center for Innovation and Technology
150 Main Street
Suite 130
Salinas, CA 93905
831-272-0661
49
High Throughput Phenotyping
Jeff Dahlberg, University of California Ag and Natural Resources (ANR) Kearney Ag Research
& Extension Center,
Parlier CA 93648
Robert Hutmacher, University of California ANR West Side Research & Extension Center,
Five Points CA 93624
Matt Colgan, Blue River Technology,
575 N. Patoria Ave., Sunnyvale, CA 94085
Chi Nguyen, Blue River Technology,
575 N. Patoria Ave., Sunnyvale, CA 94085
Christer Jansson, EMSL-Pacific Northwest National Laboratory,
Richland WA 99352
John Vogel, Department of Plant and Microbial Biology,
University of California Berkeley 94720
Jennifer Spindel,DOE Joint Genome Institute,
Walnut Creek CA 94598
Scott Staggenborg,Chromatin, Inc., 1301 East 50th Street,
Lubbock, TX 79404
Introduction
As a nation and as a world, we face the challenge of increasing the supply of biofuel
feedstock crops with lower CO2 emissions compared to petroleum-based fuels, while contending
with the impacts of climate change on agriculture such as droughts and increased soil salinity.
Sorghum [Sorghum bicolor (L.) Moench] is a biofuel crop with high drought and salinity
tolerance that is well suited to growing in arid or marginal croplands.
The Consortium for Advanced Sorghum Phenomics (CASP) is working to accelerate
breeding of biomass sorghum to maximize terminal compositional (e.g., lignocellulosic) yield
using drought and saline field conditions using novel tools for high-throughput in-field
phenotyping, together with genotyping, association mapping, and trait-prediction modeling. The
research employs an unprecedented combination of innovative technologies for field
phenotyping, and computational modeling, to arrive at early phenotypic trait associations and
molecular biomarkers with high predictive power for drought/saline tolerance and biomass yield
at maturity.
Method
Large collections of sorghum germplasm were planted at the Kearney Agricultural
Research and Extension (KARE) Center located in Parlier, CA and the Westside Research and
50
Extension (WREC) Center located in Five Points, CA (Figure 1). These two sites represent
different soil types, a sandy-loam at KARE and a clay-loam at WREC. These fields were
subjected to pre- and post-flowering drought stress as well as a controlled irrigation strategy and
were flown weekly 2 weeks after emergence with drone technology from Blue River. Based on
the phenotyping results and GWAS analyses, a subset of lines was replanted in year 3 for
additional phenotyping.
Figure 1: Pre-flowering drought stress at KARE (left, 47 days post emergence) and WREC
(right, 50 days post emergence) in 2017.
Preliminary Results
Results are being evaluated through regression analyses to develop a phenotyping
drought stress index that will be predictive of drought stress tolerance based on various plant
phenotyping measurements. These measurements are also part of a large scale genotyping
project to link phenotype with genotype expression.
51
Development of the Next Generation of Perennial Crop Modeling Tools
Brian N. Bailey, Department of Plant Sciences, University of California, Davis
One Shields Avenue, Davis, CA 95616
Phone (530) 752-7478, [email protected]
Keywords: crop modeling; decision support; horticulture; water use efficiency
Background
The long-term viability of many modern agricultural systems is dependent on its growers’
ability to adapt and respond to rapidly changing variables such as market, labor, political, and
environmental forces, as well as pest/disease pressure and equipment availability. However,
growers often rely heavily on past experience and generational knowledge in order to make daily
management decisions, which can take decades to develop. This past experience will be less
reliable as weather volatility accelerates, available resources diminish, and social/political
aspects continue to play an increasing role (Howden et al., 2007). Planting or irrigation practices
that posed little risk previously, could result in crop failure. New threats will also develop due to
increased global trade (e.g., the introduction of exotic pathogens and pests such as with citrus
greening). Traditional experimental methods or “trials” will likely not be able to keep up with the
rapid influx of management challenges growers routinely face. Recent advances in technology
and mathematical modeling could allow for the development of risk management systems that
aid growers in making decisions and acting at the sub-field to regional scales.
Computer-aided design and management in agriculture
Computational design tools have revolutionized the way that many products are designed
and manufactured in a wide range of industries outside of agriculture (Chang and Wysk, 1997).
Before such tools were available, the process of designing and testing various products was
much slower than it is today. With the advent of computational design tools, the
bottleneck of prototyping and testing has been considerably reduced by allowing for the initial
testing of designs in a simulated environment or “in silico” using computer models.
In this work, we are developing transformative computer-aided design and management
tools for agriculture analogous to computer-aided design and manufacturing tools used in
traditional engineering design and analysis. The models will accelerate overall innovation in
agriculture by allowing for rapid testing of a range of possible agricultural design or management
practices in a detailed three-dimensional simulation environment, before making the decision to
conduct a long-term trial/experiment that is costly in terms of time and money (Fig. 1).
This approach is applicable both to design of new agricultural systems, as well as more
efficiently managing current systems. For example, the sustainability of a potential new orchard
could be evaluated by running through a range of future climate scenarios to understand current
and impending challenges. Proposed management practices can also be evaluated in a simulated
environment to better understand their impacts on the agricultural system as a whole.
Rapid generation of model inputs
We have developed new techniques that use laser scanning (LiDAR) to faithfully
measure plant geometry, which feeds directly into the models. In conjunction with new
processing algorithms, the LiDAR data is able to provide information about the distribution of
52
leaf angle/orientation and leaf area (Bailey and Mahaffee, 2017), which is used to perform a leaf-
by-leaf reconstruction of the canopy (Bailey and Ochoa, 2018). We are also working on
developing platforms to integrate various public and private data sources, such as high-resolution
weather data, USDA soil classification maps, and data that growers collect as part of their field
operations.
Current model development focus
Initial efforts in developing this modeling framework was focused on providing better
understanding, prediction, and management of aerial pathogen spread in grapevine. Current
interests have also included applications related to water use efficiency in terms of amount of
carbon gained through photosynthesis per unit water loss. The modeling system developed in this
work provides a powerful tool for assessing various methods for estimation of crop
evapotranspiration, and coupling these estimates with the physiology of the plant to develop a
better understanding of how to utilize estimates of plant water status to more effectively manage
irrigation.
Future directions
One clear direction in further developing our modeling framework is to make the models
more accessible to growers by developing a user-friendly graphical user interface (GUI).
Currently, the modeling framework is geared toward research applications, and thus the current
user interface was designed with that type of user in mind.
Additionally, the modeling focus within this work will shift toward growth and yield
prediction in woody perennial cropping systems. Overall, the system was designed with
flexibility in mind, such that it lends itself to a wide range of cropping systems and processes of
interest. The ultimate goal of the system is to be able to simulate nearly any management or
design decision a grower could make, and its impact on the agricultural system as a whole.
Figure 1. Illustration of the
computer-aided agricultural
innovation process. Given an
idea or question to be explored,
the models are first used for
rapid evaluation in order to
determine which “prototypes”
should be tested via field
experiments or trials.
53
Literature Cited
Bailey, B.N. and Ochoa, M.H. (2018). Semi-direct tree reconstruction using terrestrial LiDAR
point cloud data. Remote Sensing of Environment 208:133-144
Bailey, B.N. and Mahaffee, W.F. (2017). Rapid, high-resolution measurement of leaf area and
leaf orientation using terrestrial LiDAR scanning data. Measurement Science &
Technology 28:064006
Chang, T.-C., and Wysk, R. A. (1997). Computer-Aided Manufacturing. 2nd ed. Prentice Hall,
Upper Saddle River, NJ.
Howden, S. M., Soussana, J.-F., Tubiello, F. N., Chhetri, N., Dunlop, M., and Meinke, H. (2007).
Adapting agriculture to climate change. Proceedings of the National Academy of
Sciences, 104:19691-19696.
54
2019
Session #4
Irrigation Water Use Efficiency
Session Chairs:
Michelle Leinfelder-Miles
Khaled Bali
Florence Cassel Sharma
55
Using CropManage Decision Support Tool for Improving Irrigation and Nutrient
Efficiency of Coastal Vegetables and Berries
Michael Cahn, Irrigation and Water Resources Advisor, UC Cooperative Extension, Monterey
County
1432 Abbott St., Salinas, CA 93901
Phone (831) 759-7377, fax (831) 758-3018, [email protected]
Lee F. Johnson, Senior Research Scientist, NASA ARC-CREST / CSU Monterey Bay
Earth Science Division, NASA Ames Research Center, MS 232-21
Moffett Field, CA 94035-0001
650-604-3331, fax 650-604-3625, [email protected],
Richard Smith, Vegetable and Weed Advisor, UC Cooperative Extension, Monterey County
U.C. Cooperative Extension, Monterey County
1432 Abbott St. Salinas CA 93901
(831) 759-7365, fax (831) 758-3018, [email protected]
Introduction
Vegetable and strawberry growers on the central coast of California are under regulatory
pressure to reduce nitrate loading to ground and surface water supplies. California is also
implementing the Sustainable Groundwater Management Act (SGMA) which may limit
agricultural pumping in regions such as the central coast where ground water has been
overdrawn.
Growers could potentially use less N fertilizer, address water quality concerns, and
conserve water by improving water management by weather-based irrigation, and matching
nitrogen applications to the N uptake pattern of the crop. Two tools available to growers, the soil
nitrate quick test (SNQT) and evapotranspiration (ET) data from the California Irrigation
Management Information System (CIMIS), have been shown to help better manage water and
fertilizer nitrogen in lettuce production (Cahn and Smith 2012, Hartz et al. 2000).
However, adoption of these practices has not been widespread. These techniques can be
challenging to implement, and vegetable growers have many fields for which they make daily
decisions on fertilization, irrigation, pest control, and tillage. The SNQT entails collecting a
representative soil sample, extracting the sample, and calculating soil mineral N concentration.
When deciding on an appropriate N fertilizer rate, growers also need to consider the N uptake
rate of the crop, and mineral N contributions from soil and previous crop residues. Scheduling
irrigations based on weather requires retrieving reference ET data from the CIMIS website and
determining a crop coefficient that corresponds to the crop developmental stage. In addition,
information on the soil water holding capacity and irrigation system performance is needed to
determine the optimal irrigation interval and run-time.
Web application for irrigation and nitrogen management decision support
To address many of these management challenges on a field-by-field basis, U.C.
Cooperative Extension has developed a web-based software application, called CropManage
(v3.cropmanage.ucanr.edu) to facilitate the implementation of the SNQT and ET based irrigation
56
scheduling. The software allows growers to quickly determine an optimal fertilizer N rate based
on the SNQT and crop N uptake curves and determine the amount of water to apply based on
reference ET data and modeled crop coefficients. The web application also helps growers track
irrigation schedules and nitrogen fertilizer applications on multiple fields and allows users from
the same farming operations to view and share records. Growers can export their irrigation and
fertilizer records for their fields into an excel file.
Users can access the software through a web browser on their smart phones, tablet and
desktop computers. The online tool is currently free to the public and has been supported by
grants from state agencies including the Department of Food and Agriculture and Department of
Water Resources. Although originally developed for lettuce in 2011, CropManage (CM) has
been expanded to accommodate additional commodities including broccoli, cabbage,
cauliflower, celery, cilantro, spinach, baby lettuce, bell pepper, tomato, strawberries and
raspberry. In addition, the user interface was recently improved to facilitate communication
between farm managers and field staff and improve ease-of-use on small screens. Users can
elect to view CM in English or Spanish.
A web application programming interface (API) was developed to allow CM to
communicate with other software and with weather station networks outside of California.
CropManage can be configured to automatically import and analyze flowmeter data for
monitoring irrigation applications. Soil moisture data files can also be automatically imported
and displayed. CropManage interfaces with the NASA Satellite Irrigation Management System
(Melton et al., 2012) and can automatically import estimates of crop canopy cover developed
from satellite observations (Guzman et al., 2018).
Decision support algorithms
The N fertilizer algorithm develops recommendations based on an N uptake curve
developed empirically from commercial field data, soil mineral N (SNQT data), as well as
estimates of N mineralization from the soil and residue of the previous crop. The software can
also account for nitrogen in irrigation water. To create a fertilizer recommendation, the user
enters the intended fertilization date, estimated days until the next fertilization event, and a soil
nitrate value. The model then determines the amount of N fertilizer needed to maintain optimal
growth during the interval between fertilizer events. The soil nitrate sample is compared to a
threshold value that is specific for each commodity. The soil nitrate threshold usually varies for
the different stages of growth.
The irrigation scheduling algorithm uses CIMIS reference ET data, crop coefficient
values based on fractional cover of the canopy, soil water holding capacity, and the application
rate of the irrigation system to estimate the appropriate irrigation interval and volume of water to
apply to maximize crop growth and minimize deep percolation. The algorithm was originally
based on the crop coefficient model of Gallardo et. al. (1996) for estimating evapotranspiration
of lettuce and was later adapted to other vegetable and berry commodities.
To obtain a recommended irrigation volume, the user enters the date of the next irrigation
and the software automatically obtains reference ET data from the nearest CIMIS weather station
and estimates the crop coefficient. Historical ET data are used when current data are
unavailable. The software also allows the user to select reference ET data from spatial CIMIS
(Hart et al., 2009). Spatial CIMIS values are partially based on remote sensing estimates of net
solar radiation and can provide improved spatial resolution, presumably increasing the accuracy
of crop ET estimates for fields located in a different climatic zone than the closest CIMIS station.
57
The recommended irrigation volume is based on the estimated crop ET adjusted for irrigation
system uniformity and leaching fraction, which can be customized by the user. CropManage will
also recommend the time interval to irrigate based on the irrigation system characteristics which
the user enters when initially setting up a new planting.
Maximum soil moisture tension values known to slow crop growth (eg. -30 kPa for
lettuce) are used to optimize the recommended irrigation interval. The maximum allowable
depletion of moisture between irrigations is determined using algorithms relating volumetric soil
moisture to soil moisture tension and a model for rooting depth.
Field evaluations
Field testing of CM was conducted in head lettuce, romaine, broccoli, cabbage,
cauliflower, celery, and strawberry on research farms and in commercial fields to evaluate the
decision support algorithms in terms of yield response, water use efficiency (WUE), and nitrogen
use efficiency (NUE). Results of the trials were reported in several publications and reports
(Cahn et al. 2014, 2015a, 2015b, Johnson et al. 2016a,b).
Results for field trials conducted in commercial fields demonstrated reductions of
nitrogen fertilizer rates of 30% to 40% in lettuce while maintaining commercial yield and
quality. At sites with a high concentration of nitrate (> 50 ppm NO3-N) in the irrigation water,
trials demonstrated that fertilizer nitrogen could be reduced by more than 50% of the grower’s
standard rate without yield loss in lettuce.
The CM treatment generally resulted in less consistent savings of water than for nitrogen
fertilizer for irrigation trials conducted in commercial fields. In several field trials with broccoli,
as much as a 50% reduction in water was measured for the drip phase of the crop without
reducing yields. In other commercial trials in lettuce, broccoli, and strawberry the CM
recommendation resulted in less than a 10% savings in water compared to the grower irrigation
practice. Presumably, these growers were already using efficient irrigation management
practices.
Replicated irrigation trials were conducted at research farms for broccoli, cauliflower,
celery, iceberg and romaine lettuce, and strawberry to evaluate the accuracy of the CM irrigation
algorithms during the previous five years. These trials compared yield and quality of the crops
under varying percentages of the CM irrigation recommendation (50%, 75%, 100%, and 150%
of the CM recommendation) using drip irrigation. Trials conducted in strawberry, romaine
lettuce, iceberg lettuce, and broccoli (Johnson et al. 2016a, b) demonstrated that yield and quality
were maximized by applying 100% of the CM recommendation volume of water. Results from
trials in cabbage, cauliflower and celery suggest that the CM water volume recommendation
results generally maximize WUE (and NUE) and is adequate to generate a commercial yield.
Initial findings, however, suggest that additional water application can produce somewhat greater
yield for those crops. We speculate that either the crop coefficients for these commodities are
higher than previously reported, or extra water is needed to compensate for high sensitivity of
these crops to small/transitory deficits in soil moisture. The results of these trials, along with
additional cauliflower and celery experiments pending in 2019, will be used to continuously
improve the irrigation recommendation algorithms.
58
Grower use
Grower use of the CropManage tool has steadily increased since going online in 2011.
CropManage currently supports more than 1700 registered users and provided nearly 1500
recommendations per month to users during the summer 2017 and 2018.
CropManage is used for different purposes by growers, consultants, agency and
university personnel. Some growers are interested to use CM for determining fertilizer N rates
and others are interested in using CM mainly for irrigation scheduling. Several large-scale
growers use CM to maintain records of their fertilizer applications on a per-field basis. Several
consultants and agencies have used CM to evaluate grower practices for irrigation and nitrogen
management. CropManage has been used to support nutrient and irrigation management
curriculum in community colleges and universities.
Future developments
Interest in adapting CM to crops produced in the Central Valley, other areas of the state
and other western states such as Arizona and Oregon, could potentially increase the user-base.
CropManage was recently updated to provide irrigation recommendations for perennial crops
such as alfalfa and almonds. Plans are underway to adapt CM to other tree commodities and to
continue adding new vegetable commodities.
The intent is to further develop CM as a native application so that users can enter data
from the field when they lack an internet connection. Growers have also requested a simplified
version of CM that irrigators and other farm workers can more easily navigate. Based on user
feedback, CM is continuously being updated to improve the user experience and to perform more
effectively. Ongoing training sessions are offered in various growing regions.
Literature Cited
Cahn, M.D., and R. Smith. 2012. Improving water and nitrogen efficiency in lettuce.
Proceedings of the 2012 Plant and Soil Conference, Feb. 7-8, 2012 Visalia CA. pp. 80-83.
Cahn M., Smith R., Hartz T. 2013a. CropManage: A web-based irrigation and nitrogen
management tool. 2013 California Plant and Soil Conference Visalia, CA 90-95
Cahn M., Smith R., Hartz T., Noel B. 2013b. Irrigation and nitrogen management web-based
software for lettuce production Western Nutrient Management Conference March 7-8, 2013
2013 Reno, NV 10 11-16
Cahn M., Smith R., Farrara B., Hartz T., Johnson L., Melton F., Post K. 2014. Irrigation and
nitrogen management decision support tool for vegetables and berries. U.S Committee on
Irrigation and Drainage Conference: Groundwater Issues and Water Management —
Strategies Addressing the Challenges of Sustainability USCID, March 4-7 2014 Sacramento,
California
Cahn M., Smith R., Bali K. 2015a. Irrigation and nitrogen management web-based software
lettuce production. 23rd annual CDFA Fertilizer Research and Education Program
Conference Proceedings, CDFA FREP, November 5-6 Seaside CA 67-69
https://www.cdfa.ca.gov/IS/ffldrs/frep/pdfs/2015_Proceedings_FREP.pdf
Cahn M., Hartz T., Smith R., Noel B., Johnson L., Melton F. 2015b. CropManage: an online
decision support tool for irrigation and nutrient management Proceedings of the Western
Nutrient Management Conference March 5-6, 2015 2015 Reno, NV 11 9-13
http://www.ipni.net/ipniweb/conference/wnmc.nsf/e0f085ed5f091b1b852579000057902e/4b
e3031d1d87927a85257e37004fa7a8/$FILE/WNMC2015%20Cahn%20pg9.pdf
59
Gallardo, M., R.L. Snyder, K. Schulbach and L.E. Jackson. 1996. Crop growth and water use
model for lettuce. J. of Irrig. and Drain. Eng. 122, No. 6: 354-359.
Guzman, A., F. Melton, L. Johnson, and M. Cahn, 2018. Supporting advances in agricultural
sustainability through integration of NASA SIMS and CropManage for irrigation
management support. American Geophysical Union, #H51R-1566, 10-14 Dec., Washington
DC.
Hart, Q., M. Brugnach, B. Temesgen, C. Rueda, S. Ustin, and K. Frame, 2009. Daily reference
evapotranspiration for California using satellite imagery and weather station measurement
interpolation. Civil Engineering & Environmental Systems 26:19-33.
Hartz, T.K., W.E. Bendixen, and L. Wierdsma. 2000. The value of pre-sidedress soil nitrate
testing as a nitrogen management tool in irrigated vegetable production. HortScience
35:651-656.
Johnson L.F., Cahn M., Martin F., Melton F., Benzen S., Farrara B., Post K. 2016a.
Evapotranspiration-based irrigation scheduling of head lettuce and broccoli. HortScience
51:935-940.
Johnson, L., M. Cahn, S. Benzen, I. Zaragoza, L. Murphy, T. Lockhart, and F. Melton, 2016b.
ET-based Irrigation Management in Leaf Lettuce and Cabbage: Results from 2015 Trials.
Proceedings USCID Water Management Conference, U.S. Committee on Irrigation &
Drainage, (Eds. S. Macaulay, D. Bradshaw, S. Anderson), pp. 81-86, ISBN 978-1-887903-
53-0, 17-20 May, San Diego.
Melton, F., L. Johnson, C. Lund, L. Pierce, A. Michaelis, S. Hiatt, A. Guzman, D. Adhikari, A.
Purdy, C. Rosevelt, P. Votava, T. Trout, B. Temesgen, K. Frame, E. Sheffner, and R.
Nemani, 2012. Satellite Irrigation Management Support with the Terrestrial Observation and
Prediction System: An Operational Framework for Integration of Satellite and Surface
Observations to Support Improvements in Agricultural Water Resource Management. IEEE
J. Selected Topics in Applied Earth Observations & Remote Sensing 5:1709-1721.
60
Surface Irrigation Automation and Efficiencies
Khaled Bali
Irrigation Water Management Specialist
University of California Ag and Natural Resources (ANR) Kearney Ag Research & Extension
Center,
Parlier CA 93648
https://alfalfa.ucdavis.edu/+symposium/2018/PDFfiles/Bali.pdf
61
Using Simple Graphs to Improve IWM Effectiveness with NRCS Financial
Assistance
Gregory R. Norris, USDA-NRCS
430 G Street, Davis, CA 95616
Phone (530) 792-5609, [email protected]
F. Dan Johnson, USDA-NRCS
430 G Street, Davis, CA 95616
Phone (530) 792-5625, [email protected]
Introduction
The Natural Resources Conservation Service (NRCS) is an agency within the United
States Department of Agriculture (USDA) with a specialized mission to help agricultural
producers on private and tribal lands conserve natural resources. NRCS uses a combination of
technical and financial assistance to incentivize and to assist producers to apply conservation
practices. For water resources in California, NRCS has a long history in helping producers
conserve water and believes that there is still great opportunity to conserve more water resources
through Irrigation Water Management (IWM). IWM is one of many conservation practices that
NRCS uses to help producers conserve irrigation water.
NRCS is moving to a more strategic approach in how to use IWM to help producers
understand the fate of irrigation water applied. If the underlining objective in applying IWM is
to use measured data to make irrigation timing and amount decisions to control deep percolation,
then NRCS would like to focus more on the soil, where the producer applies the water, and the
plant, the intended recipient of the applied water. The social aspect of this new approach is
changing from NRCS teaching producers how to determine when and how much to irrigate, to
NRCS helping producers self-assess and determine what is not working well in their current
irrigation strategy. This strategy will create a mechanism for measuring success in terms of
controlling water lost to deep percolation, which has been typically missing.
Using this newer strategy, NRCS plans to use a standardized soil water status graph to
communicate important concepts of measured crop water use, soil moisture content, irrigation
event data, and soil water holding capacity into a single, cohesive display. The graph will
present data so that producers evaluate their own management and determine future courses of
actions. NRCS offers the graphic soil water status system as something that can be supported
technically and programmatically and believes it should serve as a foundation or backdrop piece
of the producer’s irrigation strategy.
Past IWM Strategy
In the past, NRCS has used IWM to teach producers how to use crop water use, soil
moisture, and soil property data to calculate when and how much to irrigate. Producers are
expected to change from what they are currently doing to using the new data-driven process.
Unfortunately, few producers followed through with implementing recommendations whether
due to a poor understanding of the process, the need to perform calculations, time requirements,
scheduling conflicts with other farming operations, or a question of perceived value, all of which
led to lack of motivation for implementation.
62
New IWM Strategy
The approach NRCS is now taking recognizes that producers, by the nature of their work
as managers, are problem solvers. They monitor the farming operation for problems and are
motivated to act when problems arise. By this approach, NRCS focuses on assisting the
producer with acquiring the ability to evaluate the results of their irrigation decisions. The
ability to see results provides motivation to continue monitoring and to make any needed
adjustments to timing and amount decisions when problems are discovered, or at least helping
producers to self-calibrate their irrigations. NRCS assistance includes assisting producers
determine if results are good or bad, selecting an evaluation mechanism, and acquiring
equipment and services to use that mechanism.
The graphical display of soil water status provides such a mechanism (See Figure 1). The
addition of Field Capacity and Allowable Dryness threshold lines provide criteria that the
producer can use to determine if a problem exists with over- or under-irrigation. If the soil water
status line is above the field capacity line, then deep percolation may be occurring at that time. If
the soil water status line is below the allowable dryness line, then the crop may be experiencing
stress at that time. The addition of irrigation event data (times and amounts) allows the producer
to determine what caused the exceedance of field capacity (X hours of run time was too long or
Y days between irrigations was too frequent) and depletion below the allowable dryness line (Z
days between irrigations was too long or W hours of run time was too short). These features
allow the producer to easily evaluate past irrigation timing and amount decisions.
Figure 1. Example Soil-Water Status Graph.
When looking ahead to the next irrigation event (or series of irrigations) the producer can
observe the current trend (slope of the soil water status line) to plan when the next irrigation
Soil Water Status
63
should occur (when the soil water status line approaches the allowable dryness line). The
producer will naturally adjust this projection based on their knowledge of forecasted weather.
The producer can select future run times using what they’ve learned and looking back at how soil
moisture increased in response to prior run times. Use of the graph to adjust irrigation frequency
and amount is a trial and error process and often requires no calculations.
The data is passive in that it doesn’t explicitly tell the producer when to irrigate and how
much to apply, but instead makes the data available in a visible, actionable format so that they
can weigh consequences of changing irrigations to work around farm operations or water supply
availability constraints. In addition, the graph serves as an effective point of discussion between
NRCS and the producer. There are four key elements needed for the graph.
The Soil Water Status Line(s)
There are two methods to track soil water status: by using real data from soil moisture
sensors, or by calculating a water balance from data points using a combination of
evapotranspiration (ET) measurements and water application (irrigation and rainfall) data. If the
line is determined using real data, the sensors must be installed at key depths in the root zone
(soil profile) to capture water status variability with depth. Each sensor should be represented by
a unique soil water status line. If the line is determined using a water balance, ET is typically
obtained from the California Irrigation Management Information System (CIMIS). The water
balance approach is valid only where there is no irrigation runoff and there is no other source of
water such as from a perched or shallow water table. In contrast to the soil moisture sensor
method, where soil water status is measured at various depths, ET methods provide one value
that integrates moisture conditions for the entire root zone so there is always only one curve.
The Field Capacity Threshold Line
The field capacity line serves the vital role of telling the producer when water is being
lost to deep percolation because of their irrigation decisions, a threshold they generally don’t
want to cross. In addition, knowing where the “full” mark is in their soil reservoir enables them
to determine whether they are using the full storage capacity. The placement of the field
capacity line depends on the method used to track soil water status.
When soil moisture sensors are used, manufacturers offer default sensor readings at
which field capacity likely occurs for a given soil texture. A more accurate method, which
works on many but not all soils, is to interpret the shape of the curve following a full irrigation
event. When using soil moisture sensors at various depths, variation in soil properties with depth
will result in field capacity values also varying with depth. In other words, each soil layer could
have an associated field capacity line. However, most graphing software only allows for
establishing one field capacity line. Because deep percolation is defined as excess water moving
beyond the “bottom” of the root zone, it’s important that field capacity be determined and
displayed for the soil in which the deepest sensor is placed.
The water balance method requires the threshold line to be calculated as a total for the
entire root zone. Therefore, there will always be just one field capacity line on ET-based graphs.
The NRCS Web Soil Survey includes a Soil Properties feature that calculates cumulative field
capacity water content (inches) for the user defined root zone depth. An important consideration
for annual crops is that the total root zone field capacity water content will increase as the root
zone expands with growing roots. Therefore, soil water content at field capacity will increase
during the early root development stage of crop growth.
64
The Allowable Dryness Threshold Line
The purpose of the allowable dryness line is to illustrate the lower (dry) limit or threshold
of desired soil water content. If the producer is looking ahead to the next irrigation, the
allowable dryness line and the current soil water status trend allows them to project when the
next irrigation should occur. Looking back, the producer learns whether they let it get too dry
(waited too long) or could have waited longer before they irrigated. Positioning the allowable
dryness threshold is a management decision based on crop production and quality goals and soil
or farm constraints.
The most common interest is to know the soil water content at which crop water stress
begins to occur, typically something to be avoided. From an IWM perspective, the allowable
dryness line may provide a producer, who is very cautious about water stress, a reliable reason to
wait to start the next irrigation, reducing the likelihood of irrigating sooner than necessary which
may result in deep percolation water loss.
Knowing the soil water status at the onset of plant stress may not be considered important
by producers who irrigate relatively frequently such as daily or multiple times per day.
However, in the event of unforeseen circumstances, we believe there is value in the producer
knowing how dry they could allow the soil to get before experiencing plant water stress.
Although the producer’s primary interest is typically in avoiding plant water stress, they
may have additional reasons to limit how dry they allow the soil to get. For example, some
micro irrigation systems have such a low application rate that it may not be able to “catch up”
during periods of high ET if the soil water content gets too low. Also, if the system application
rate is high and soil water intake rate is low the producer may want to restrict how dry it gets to
avoid runoff associated with long run times.
Indicator(s) of Timing and Amount of Water Applied
NRCS has long encouraged producers to record when they irrigate and how much they
apply. The purpose of showing them on the graph is to enable the producer to compare how
much water they applied to how much the crop used. Applying more water than the crop used
since the last irrigation indicates that there may be a problem that needs to be addressed. The
idea is that they learn from this exercise and adjust, if needed, for future irrigation decisions
toward meeting deep percolation and crop stress objectives.
What the Producer Learns from Their Graph
When the producers chooses to use sensors to develop the status line, NRCS describes the
need for sensors at a minimum of three key depths within the root zone of permanent crops, each
to serve a different purpose. The first one at a “shallow” depth to monitor moisture conditions in
the most active part of the root zone, the second at about the 2/3 depth to allow the producer to
see if they are taking advantage of deep water storage and the third at the bottom or just below
the root zone to monitor the occurrence or risk of deep percolation water loss.
When the producer is new to using graphs, they probably can’t specifically describe what
they expect to learn from looking at their graph. The producer needs to progress along the
learning curve of how soil moisture conditions respond to irrigation timing and amounts. A
reasonable approach in the beginning is to simply irrigate as they always have and then see how
the soil water status graph responds. Once they begin to understand and gain some level of trust
65
in the data, the producer should then be able to assess how the sensors at different depths respond
and then correlate that to plant response.
If the producers chooses to use a water balance approach to develop the water status line,
then ET-based graphs include only one soil water status line that represents the volumetric water
content of the entire root zone. Accordingly, the Field Capacity and Allowable Dryness lines
also represent water content totals for the root zone.
If the producer irrigates using a set schedule (e.g. every 3 days) during the growing
season, the soil water status line for this sensor should show a cyclic pattern of progressive
drying in the days following irrigation and/or rainfall events and rapidly re-wetting following
effective rainfall and/or irrigation events. Looking at the results of recent irrigation events, the
producer should be interested in the proximity to and length of time the water content dips down
toward the “dry” threshold level they have established. If they see a pattern of exceeding this
threshold, they may start thinking about the need to irrigate more frequently. Next, they may
look to confirm that the soil reservoir was filled at this depth following each irrigation as
indicated by the water status line rising above the Field Capacity line. In addition, the producer
can look at the current rate of daily drying and project when the next irrigation event should
occur. The longer term (multiple irrigation events) trend should be of interest to let the producer
know if they are creeping toward the “too wet” or “too dry” thresholds.
If the producer irrigates at a high frequency (daily or even multiple times each day), the
line may appear almost smooth. In this case the producer will observe the trend of the line over
several days of irrigation. Lines that are trending toward Field Capacity or above may indicate
the risk of depriving the plant of oxygen and encouraging disease problems from being “too
wet”. Conversely, lines that exist at or are trending toward, the dry threshold may indicate the
onset of undesirable water stress. The producer may conclude they need to adjust their
frequency and/or run times to move the line to a more desirable location within the range of
desirable soil water status.
An additional consideration is that the establishment of the Field Capacity threshold is
not an exact science. It would be prudent to keep the soil water status line somewhat below the
Field Capacity as an assurance that deep percolation is not occurring. In other words, don’t try
to completely “refill” the soil reservoir within the root zone with each irrigation.
An important exception to all of this is the occasion when the producer strategically
applies a larger amount of water to meet a salt leaching requirement. In this case, exceeding FC
of the root zone, by some amount, is an objective.
What NRCS Learns from the Producer’s Graph
The purpose of the graph is for the producer to have actionable data with which to
manage their soil water reservoir. For NRCS, the graph provides a prompt for the ongoing
technical assistance discussion with the producer. Secondarily, the graph can also serve to
demonstrate whether the producer is effectively implementing the practice from a financial
and/or technical assistance program perspective.
Summary
The root zone is where the producer puts the water with the intent of it being stored for
future use. Crops respond to root zone moisture levels. IWM includes monitoring the fate of
infiltrated water and soil moisture change in response to ET and irrigation. The use of these soil-
water relationships graphs expanded by NRCS to better illustrate the interaction between soil
66
water status, field capacity, crop stress levels, and irrigation data, and to serve as a tool to
educate and inform producers and others about how all of these factors should fit together to
influence irrigation decisions. Soil moisture graphs allow producers to quickly evaluate root
zone water status as it relates to “too wet” and “too dry” water levels. Any need to change their
irrigation strategy is identified and future irrigation events can be planned in the context of
farming operations which has the potential of conserving water.
67
2019
Session #5
IPM: Insect Pests and Disease
Session Chairs:
Rachel Naegele
Jeff Dahlberg
Karen Lowell
68
Management of Sugarcane Aphid in CA Forage Sorghum
Nicholas Clark1, David Haviland 2, Brian Marsh2 and Jeffrey A. Dahlberg3. 1UC Cooperative Extension, Kings, Tulare, & Fresno Counties, 680 N. Campus Dr., Ste. A,
Hanford, CA 93230, (559) 852-2788, FAX (559) 582-5166, [email protected]; 2 UC Cooperative Extension, Kern County, 1031 S. Mount Vernon Ave., Bakersfield, CA 93307,
(661) 868-6200, [email protected], [email protected]; 3UC Kearney Agricultural Research and Extension Center, 9240 S. Riverbend Ave., Parlier, CA
93648, Phone (559) 646-6060, [email protected]
Introduction
Sugarcane aphid, Melanophis sacchari, is a newly introduced insect pest of California
sorghum. It was first reported in California during the summer of 2016 when multiple growers in
the southern San Joaquin Valley reported difficulties in controlling aphids with traditional
organophosphate insecticides. By the end of August, CDFA identified the species as sugarcane
aphid (SCA), a new exotic pest that within the past few years had become established and was
spreading throughout southern states. The strain of SCA found in California was first reported in
Texas and Louisiana in 2013, and by 2014 was found in 11 southern states from Texas to
Florida.
Sugarcane aphid can easily be distinguished from other aphid species due to their yellow
color with black feet, tips of antennae and cornicles (tailpipes) that point upward from the rear of
the insect. This is in contrast to greenbug and other aphid species in sorghum that have a
greenish appearance. Host plants for sugarcane aphid include sugarcane, sorghum, sudangrass,
sorghum X sudangrass hybrids, and the weed Johnsongrass (Sorghum halepense). It has not been
found on corn.
Since 2014 there has been a significant amount of research on SCA conducted in
southern states. This research has generated information on SCA identification, life cycle,
reproductive potential, treatment thresholds, biological control and treatments. Portions of this
information have been very useful in helping California growers. However, other information,
particularly related to crop loss and treatment thresholds has been less transferrable due to
differences between southern production systems for grain and California production systems
directed towards forage. In one applicable study, Bowling et al. (2016) studied the effects of
sulfoxaflor on SCA in forage sorghum, but was unable to detect differences in hay quality within
treated and untreated plots with maximum aphid densities around 25 aphids per week. In another
study, Heguy at al. (2017), collected data from 16 dairies and concluded that significant
reductions in starch and non-fibrous carbohydrate and increases in acid-detergent fiber, ash, and
crude protein probably resulted from severe SCA infestation.
The objective of our project was to study the impacts of insecticide treatments on SCA
populations and gain a better understanding of how aphids affect crop yield and feed quality in
forage sorghum.
69
San Joaquin Valley Insecticide Efficacy Studies
Methods
During 2017 and 2018 we conducted three field trials in Shafter or Five Points, CA, to
evaluated the impact of insecticide treatments against SCA. Field sites were planted each June to
the sorghum cultivars NK-300 in Shafter or Silo King in Five Points at 100,000 seeds/acre to
moisture on 30” beds. Fertilizer, irrigation, and weed management programs were executed
according to industry standard practices for the region. Plots were organized into a randomized
complete block design with four replications (Table 1).
Table 1. Sugarcane Aphid Insecticide Trial Treatments
Year Site Insecticide Rate Unit/ acre
Application method
2017 Shafter UTC N/A N/A N/A Flupyradifurone 17% (Sivanto Prime) 4 fl oz Foliar Flupyradifurone 17% 7 fl oz Foliar Sulfoxaflor 50% (Transform WG) 2 oz Foliar Malathion 57% (Malathion 57%) 24 fl oz Foliar Dimethoate 43% (Dimethoate 4EC) 16 fl oz Foliar Chlorpyrifos 40% (Lorsban Advanced) 32 fl oz Foliar
2018 Shafter UTC N/A N/A N/A Flupyradifurone 17% 7 fl oz Foliar Flupyradifurone 34% (Sivanto HL) 3.5 fl oz Foliar Sulfoxaflor 50% 2 oz Foliar Afidopyropen 5% (Sephina) 6 fl oz Foliar Afidopyropen 5% 12 fl oz Foliar Dimethoate 31% 24 fl oz Foliar Dimethoate 31% + Flupyradifurone 34% 24 + 1.75 fl oz Foliar
2018 Five Points UTC N/A N/A N/A Flupyradifurone 34% 4 fl oz planting Flupyradifurone 34% 5 fl oz planting Flupyradifurone 34% 2.5 fl oz sidedress Flupyradifurone 34% 4 fl oz sidedress Flupyradifurone 34% 3.5 fl oz Foliar
Sugarcane aphid were collected from commercial fields in Corcoran and Hanford, CA,
transported to the research plots, and distributed onto the sorghum leaves. Aphids populations
were allowed do get established in the field and increase naturally for approximately three weeks
before foliar treatments were applied. In the Five Points 2018 study, soil applied treatments were
made before introducing aphids to the experimental plots.
Foliar insecticide applications were made at the initiation of sorghum heading using a
high clearance spray rig with an 8 row boom and drop nozzles. Aphid populations were
monitored weekly through harvest by counting the number of aphids on 10 to 20 mid-canopy
leaves per plot.
70
Harvest was performed at dough stage in October, using an Almaco small-plot, 2-row
forage chopper in the middle two rows of each plot. Sub-samples of chopped sorghum from each
plot were collected to calculate moisture content. These sub-samples were then sent for feed
quality analysis.
Results and discussion
Aphid population, 2017. Flupyradifurone 17% (Sivanto Prime) applied at the rates of 4
and 7 fl oz/acre reduced cumulative aphid-days by 78 and 92%, respectively. However, this
reduction was not significant due to equipment malfunctions that only allow data to be collected
from two replications. Cumulative aphid-days in plots treated with sulfoxaflor (Transform WG)
were similar to the untreated check and broad-spectrum materials tested. Broad-spectrum
insecticides including malathion, dimethoate and chlorpyrifos (Lorsban Advanced) all resulted in
less than a 50% reduction in cumulative aphid-days. There was only one day (34 DAT) when
aphid-days were significantly impacted (P = 0.024) by insecticide treatment, and that day
appears to be anomalous within our data set.
Aphid population, 2018, Shafter. Both formulations of flupyradifurone (Sivanto Prime &
Sivanto HL) showed the best control of aphids throughout the season (Figure 1). Afidopyropen
(Sefina) and Transform offered good control by keeping the aphid population below the
treatment threshold of 50 aphids/leaf throughout the season. Dimethoate + Sivanto HL also
exhibited good control of aphids throughout the season, but Dimethoate alone performed worse
than the untreated control (Figure 1).
Figure 1. Impact of insecticide treatments on sugarcane aphid populations, Shafter 2018.
Aphid population, 2018, Five Points. All of the soil treatments of Sivanto HL controlled aphid
populations well. At approximately 5 weeks after aphids were introduced into the plots, the
0
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100
120
PRE 5 DAT 9 DAT 14 DAT 19 DAT 22 DAT 28 DAT 34 DAT 41 DAT 48 DAT 54 DAT
Ap
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Sefina 6 Sefina 12 Dimethoate Dim_Siv
71
Sivanto HL sidedress treatments broke efficacy and the populations exceeded the treatment
threshold. The foliar application of Sivanto HL controlled aphid populations throughout the
season (Fig. 2).
Figure 2. Impact of in-furrow applications of Sivanto on sugarcane aphid, Five Points, 2018.
Data suggest that Sivanto is currently the best candidate for control of sugarcane aphid in
California forage sorghum. This is consistent with data collected from multiple trials on grain
sorghum in the southern US. Also consistent with data from the south is that broad spectrum
insecticides, although less expensive than Sivanto, do not provide sufficient control to justify
their use. They are also known to kill predatory insects that assist in biocontrol of aphids.
Transform and Sefina, which are not registered products in CA, provided satisfactory control of
the aphid. One year of data suggests that soil application of Sivanto HL either at planting or at
side dress are good means of control, but sidedress applications may require a later foliar
application depending on crop stage and later aphid populations. Soil applied uses of Sivanto are
not yet registered on sorghum in CA.
Yield, 2017. Treatments with Sivanto Prime applied at 4 and 7 fl oz had the highest
average yields, followed by Transform WG, which was similar to Dimethoate (Figure 3). The
untreated check and broad-spectrum insecticide treatments had lower yields. No treatment
differences had a statistically significant impact on yield, and this was probably due to data only
being collected from two replicates. Data from 2018 are still being analyzed.
Feed quality, 2017. Samples from two replicates of each treatment were sent to Rock
River Laboratory to be evaluated by wet chemistry analysis for ash, crude protein, neutral-
detergent fiber, 30 hour in vitro neutral-detergent fiber digestion, acid-detergent fiber, lignin,
0
50
100
150
200
250
300
350
400
4 DAI 11 DAI 4 DAT 7 DAT 14 DAT 21 DAT
Su
garc
an
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ids
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Siv HL in-furrow 4
Siv HL in-furrow 5
Siv foliar 3.5
Siv HL side-dress 2.5
Siv HL side-dress 4
72
starch. No significant differences were found between treatments for any of the feed quality
constituents tested (Table 2). Feed quality data from 2018 are still being analyzed.
Figure 2. Impact of insecticide treatments for sugarcane aphid on forage sorghum yield, Shafter,
2017.
Table 2. Proximal analyses of feed quality constituents, Shafter, 2017.
Acknowledgments
Special thanks to all of the technical support and data collection performed by Stephanie
Rill (Research Associate), Chelsea Gordon (Research Associate), and Jorge Angeles (Research
Associate). Walter Martinez (Agriculture Technician) and the WSREC field operations crew are
appreciated for their work on equipment and field management. This research was made possible
by contributions from Bayer CropScience, Dow AgroSciences, and BASF
0
5
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UTC Sivanto 4oz Sivanto 7oz Transform Malathion Dimethoate Lorsban
Yie
ld a
t 70%
MC
(T
on
s/acr
e)
% DM ± SEM
Treatment CP ADF aNDF Fat (EE) Ash Lignin Starch NDFD
30
uNDF
30om NFC
UTC 9.2 31.2 44.4 2.4 10.2 5.5 19.0 28.5 27.9 35.3
Sivanto 8.7 31.1 41.7 2.1 10.1 6.3 23.5 34.6 24.0 38.8
Sivanto 8.5 32.3 43.3 2.3 10.2 5.4 23.6 33.4 25.5 37.1
Transform 8.8 29.2 40.1 1.9 9.7 4.5 26.9 32.3 24.0 40.9
Malathion 7.4 32.5 47.1 2.3 10.2 4.8 15.0 40.0 24.9 34.6
Dimethoate 8.2 33.4 46.2 2.1 10.2 5.5 16.0 37.6 25.5 34.8
Lorsban 8.9 29.2 39.4 2.2 9.7 4.7 26.7 33.6 23.1 41.2
No statistical differences were found between treatments at α = 0.05.
73
Tomato Resistance-Breaking Tomato spotted wilt virus Strain: Biology and
Management in Central California
Thomas Turini, UC Agriculture and Natural Resources, Vegetable Crops Advisor,
Fresno County 550 E. Shaw Avenue, Fresno, California 93710
[email protected] 559-375-3147
Scott Stoddard, UC Agriculture and Natural Resources, Vegetable Crops Advisor in Merced and
Madera and County Director in Merced.
Robert Gilbertson, UC Davis, Professor in Department of Plant Pathology
Introduction
Tomato spotted wilt virus (TSWV) is responsible for economic damage to processing and
fresh market tomatoes in California and in most tomato production areas globally. Tomato plants
infected within several weeks following transplanting are stunted and chlorotic with necrotic
lesions; they produce no fruit or a few distorted fruits. At intermediate stages of plant
development, infections result in systemic infections with bronzed or chlorotic and necrotic
foliage and distorted fruit with abnormal coloring, and yield is typically reduced. Infections that
occur at later stages of plant development may result in symptoms that are limited to a single
shoot on an otherwise healthy plant although some fruit may exhibit symptoms. Early infections
result in the greatest economic damage on processing tomatoes while infections occurring much
later in the season may inflict substantial damage to fresh market tomatoes.
Tomato spotted wilt virus is transmitted by thrips. Nine species of thrips are capable of
transmission (Whitfield et al., 2005). In the Central San Joaquin Valley, Western flower thrips
(Frankliniella occidentalis) is most commonly associated with tomatoes. The insect must acquire
the virus by feeding on an infected plant as an immature to be capable of transmission of TSWV
as an adult (Whitfield et al., 2005).
Tomato spotted wilt virus is reported to infect 1030 plant species (Parrella et al., 2003).
Srinivasan et al. (2014) reported that weeds are the primary means of overwintering of
Frankliniella fusca and TSWV in Georgia. In the San Joaquin Valley, TSWV was frequently
associated with prickly lettuce (Lactuca serriola), Sowthistle (Sonchus spp.) in January and
February (Gilbertson, 2012). However, the virus has also been detected in other winter weeds
including little mallow (Malva parvaflora), Mustard (Brassica spp.), London rocket (Sisymbrium
irio), Wild Radish (Raphanus raphanistrum), and pineappleweed (Chamomilla suaveolens).
Chemical control of Western flower thrips is challenging because population densities
increase very rapidly, they have high fecundity and short generation time, and few insecticides
consistently reduce population densities (Reitz, 2009). Furthermore, even the best performing
materials have failed to deliver commercially acceptable levels of control under high thrips
population densities if they are infected by TSWV (Turini et al., 2017). Drip injected neo-
nicotinoids have not demonstrated significant reduction in thrips densities or in disease
incidence. However, rotations between dimethoate and spinetoram have been effective in
reducing disease incidence (Turini et al., 2017).
74
An integrated management program to limit damage caused by TSWV includes
sanitation, site selection, thrips control and plant resistance (Gilbertson et al., 2013). However, in
2016, a strain of the virus caused disease in tomato varieties with the TSWV resistance gene
(SW5) in Fresno County (Batuman et al., 2017). Similar SW5 resistance-breaking strains were
documented in Europe and other parts of the world, but this is the first report in the Continental
United States. Distribution and epidemiology of the Sw5 resistance-breaking strain of TSWV
was studied in the Central San Joaquin Valley tomato production area from 2016-2018.
Materials and Methods
Distribution of the resistance-breaking strain was evaluated through regional
observations. Winter hosts were inspected in areas where high levels of resistance-breaking
strain were detected during the previous season. Weed and crop inspections were conducted in
three production areas (Firebaugh, Cantua Creek and Huron) in 2017 and in six production areas
(North Firebaugh, South Firebaugh, Mendota, Cantua Creek, North Huron, South Huron in 2018.
In January or February, weeds/crops in those areas were scouted. Samples of symptomatic and
asymptomatic weeds were tested for presence of the resistance breaking strain.
During the tomato production season, samples from commercial fields exhibiting TSWV
symptoms were collected and tests were performed in Robert Gilbertson’s laboratory to identify
the strain present. Extension personnel collected samples from important tomato production
areas and in areas from which commercial crop consultants contacted extension personnel
regarding the presence of the virus at levels of potential economic importance.
In 2017 and 2018, in six sites in the San Joaquin Valley where the resistance-breaking
strain was previously reported, 34 commercial processing tomato varieties were examined for
presence of TSWV symptoms. All trials were transplanted from mid-Apr to early May by seed
company personnel from either Ag Seeds or TS&L. Trials were managed by the commercial
opperators and all were irrigated with buried drip. Trials were evaluated within 2 weeks of
harvest from late-July through mid-Aug. Incidence of TSWV symptoms was categorized by the
character of symptom expression. Categories included a) mild - symptom expression limited to
single shoot, b) moderate - symptom expression on a few shoots and fruit set late in the season,
c) moderately severe - symptoms throughout the plant with reduction in plant size and d) severe -
plant severely stunted with no fruit or few distorted fruits. Plots were from 7 to 10 meters in
length and the number of plants in each plot were recorded. Percentage of plants exhibiting
symptoms was calculated, Analysis of Variance performed and Least Significant Difference at
P=0.05 is presented. From four of the six sites, three plant samples were collected from each of
seven to nine plots and the strain present was determined.
Results
Resistance-breaking strains of TSWV were detected in winter in 2017 and 2018. In 2017,
the resistance-breaking strains were present in TSWV-symptomatic sowthistle weeds collected
from both Cantua Creek and Huron (Table 1). In 2018, no symptomatic weeds were detected and
only one symptomless sowthistle plant tested positive for the wild type strain, but 71% of the
TSWV-infected lettuce collected from Cantua Creek was identified as being the Sw5 resistance-
breaking strain (Table 2).
75
In spring and summer of 2017 and 2018, distribution of the Sw5-resistance breaking
strain increased. In 2017, the resistance breaking strain was documented in Five Points, south of
Huron, Mendota, Helm and previously un-documented areas within Firebaugh (data not shown).
In addition, in 2017, Sw5 resistance breaking strain was documented in Merced and Santa Clara
Counties. In 2018, distribution continued to increase within Fresno County and was documented
for the first time in Kings and in Kern Counties (Table 3). It has been consistently detected in
plants without the Sw5 gene including in tomatoes lacking Sw5 and in weeds and in other crops
(Table 3).
Among the 34 varieties included in one trial in 2017 and five in 2018 in Fresno and
Merced Counties, there appeared to be differences in terms of TSWV incidence although
variability was high. In all trials the symptom expression was primarily in the categories of mild
or moderate with very few plants showing moderately severe levels and severely impacted plants
were not seen (Figures 1 and 2). The four varieties that lacked Sw5 were among the entries with
the highest incidence, however there were a few with Sw5 that had numerically higher levels of
disease than those lacking the gene (Figure 1). There were few varieties that had significantly
higher levels of TSWV than others, but most varieties were had intermediate levels of disease
based on Least Significant Difference at P=0.05 (Figure 2). In 2017, the varieties lacking Sw5
were infected with the wild type strain; the resistance breaking strain was consistently associated
with the Sw5 varieties (Table 4). However, in 2018, only the resistance breaking strain was
detected regardless of the resistance status of the entries (Table 5).
Summary
Potential persistence of resistance-breaking TSWV: Detection in sow thistle and lettuce
in winter, as well as the increased distribution of the virus from 2016-2018 and the prominence
of the resistance-breaking strain in hosts lacking Sw5 suggests that the SW5-resistance breaking
strain was dominant by the end of the tomato season in 2018. Coupled with the widespread
movement of both the fresh market and processing tomato industries toward nearly exclusive use
of Sw5 varieties, it is likely that it will remain a production challenge into the future.
The most effective TSWV control strategy is an integrated management program.
Sanitation: Reduce weed densities and till susceptible crops immediately after harvest. If
sanitation is not possible prior to tomato planting, consider treating the weeds with insecticide
before tilling or applying herbicide. Identify high risk situations: If possible, avoid planting near
a known virus source that cannot be addressed otherwise.
Insecticides: Foliar applications of Radiant and dimethoate can reduce TSWV levels. However,
insecticide applications may not keep disease below commercially acceptable levels under high
pressure.
Currently, there is no alternative to SW5 in commercial varieties. There are other
approaches to resistance being tested under greenhouse conditions with plans to evaluate these
lines under field conditions in 2019.
76
ACKNOWLEDGEMENTS:
The research on which this note is based is supported by California Tomato Research
Institute. Those who have made major contributions on this research project included Ozgur
Batuman, Monica Macedo, Diane Ullman, Michelle LeStrange and Brenna Aegerter.
Sources Cited:
Batuman, O., Turini, T.A., Oliveira, P.V., Mellinger, H.C., Adkins, S. and Gilbertson, R. L.
(2017). "First report of a resistance-breaking strain of Tomato spotted wilt virus infecting
tomatoes with the Sw-5 tospovirus-resistance gene in California." Plant Disease.
Gilbertson, R.L., Batuman, O., LeStrange, M., Turini, T.A., Stoddard, C.S., Miyao, E. and
Ullman, D.E. (2013). “Tomato spotted wilt disease: Detection, epidemiology and integrated pest
management.” UC IPM Pamphlet.
Gilbertson, R.L. (2012). “Virus diseases of importance in tomatoes.” Presentation at Five Points
winter vegetable crops pest management. Unpublished.
López, C., Aramburu, J., Galipienso, L., Soler, S., Nuez, F. and Rubio, L. (2011). “Evolutionary
analysis of tomato Sw-5 resistance-breaking isolates of Tomato spotted wilt virus.” Journal of
General Virology 92: 210-215.
Parrella, G., Gognalons, P., Gebre-Selassie, K., Vovlas, C., and Marchoux, G. (2003). “An
update of the host range of Tomato spotted wilt virus.” J. Plant Pathol. 85:227-264.
Peiró, C., Cañizares, C., Rubio, L. and Sánchez-Navarro, J.A. (2014). “The movement protein
(NSm) of Tomato spotted wilt virus is the avirulence determinant in the tomato Sw-5 gene-based
resistance.” Molecular Plant Pathology 15(8)
Reitz, S.R. (2009). “Biology and Pest Status of Western flower thrips.” Florida Entomologist.
92:7-13.
Srinivasan, R., Riley, D., Diffie, S. and Culbreath, A. (2014). “Winter weeds as inoculum
sources of Tomato spotted wilt virus and as reservoirs for its vector, Frankliniella fusca
(Thysanoptera: Thripidae) in Farmscapes of Georgia.” Environmental Entomology. 43:410-420.
Turini, T.A., LeStrange, M., and Gilbertson, R.L. (2017). "Thirps management in processing
tomatoes and influence on Tomato spotted wilt virus symptom incidence in Central California."
Acta Horticulturae. 1159, 117-124.
Whitfield, A.E., Ullman, D.E. and German, T. L. (2005). “Tospovirus-thrips interactions.”
Annual Review of Phytopathology. 43:459–89
77
Table 1. Fresno County, Jan-Mar 2017, detection of TSWV in putative winter hosts in areas with
high levels of Sw5 resistance-breaking TSWV in Fall 2016.
Common
name
Scientific name Total
samples
TSWV + wild type resistance-breaking
Alfafa Medicago sativa 5 0 Xxx xxx
Chenopodium Chenopodium sp. 3 0 Xxx xxx
Lettuce Lactuca sativa 1 0 Xxx xxx
Malva Malva sp. 2 0 Xxx xxx
Mustard Brassica sp. 1 0 Xxx xxx
Pigweed Amaranthus sp. 1 0 Xxx xxx
Pineapple
weed Matricaria sp. 5 0 Xxx xxx
Prickly lettuce Lactuca sp. 2 0 Xxx xxx
Sowthistle Sonchus sp. 39 6 (15%) 2 (34%) 4 (66%)
Table 2. Fresno County, Jan-Mar 2018, detection of TSWV in putative winter hosts in areas with
high levels of Sw5 resistance-breaking TSWV in Fall 2017.
Common name Scientific name Total
samples
TSWV
+
wild
type
resistance-
breaking
Horse weed Conyza canadensis 1 0 xxx Xxx
Groundsel Senecio vulgaris 7 0 xxx Xxx
Kochia Bassia scoparia 1 0 xxx Xxx
Lambs quarters Chenopodium album 1 0 xxx Xxx
Lettuce Lactuca sativa 16 14 10
(71%) 4 (29%)
Malva Malva sp. 7 0 xxx Xxx
Mustard Brassica sp. 1 0 xxx Xxx
Pigweed Amaranthus sp. 1 0 xxx Xxx
Prickly lettuce Lactuca sp. 9 0 xxx Xxx
Sowthistle Sonchus sp. 42 0 xxx Xxx
78
Table 3. Status of TSWV Sw5 resistance from commercial fields in Central California, spring
and summer, 2018.
0
2
4
6
8
10
12
14
16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
Inci
den
ce (
%)
mild moderate moderately severe severe
No Sw5 Varieties with Sw5
No.
samples
Sw5
resistnc
e-
breakin
g
Wild
type
Processing tomato susceptible, 22 Apr, Huron 3 2 1
Processing tomato, 26 Apr, Five Points 1 1 0
Fresh market tomato Sw5, 2 May, Huron 5 5 0
Fresh market tomato Sw5, 4 May, Firebaugh 8 8 0
Processing tomato susceptible, 22 Apr, Huron 3 2 1
Processing tomato Sw5, 3 Jun, Kern Co. 6 3 0
Peppers 8 June, Helm 8 6 2
Processing tomato Sw5, 26 Jun, Stratford (Kings Co.) 4 3 0
Processing tomato Sw5, 26 Jun, Corcoran (Kings Co.) 5 4 0
Fresh tomatoes Sw5, 13 Aug San Joaquin (Fresno Co.) 10 8 0
Processing tomatoes susceptible, 30 Aug, Coalinga 10 6 4
Orthogonal Contrasts
No Sw5 vs. Sw5 varieties
P= 0.0173
79
Figure 1. Levels of Tomato spotted wilt virus symptoms among 34 commercial processing
tomato varieties compared based on the presence of Sw5 gene, 2017 and 2018 in Fresno and
Merced Counties.
Figure 2. Levels of Tomato spotted wilt virus symptoms among 34 commercial processing
tomato varieties in 2017 and 2018 in Fresno and Merced Counties.
Table 4. Strains present in commercial variety trial, 2017 Fresno County.
Variety SW5 in variety Strain detected
H1015 - Wtz
BQ273 + Rby
N6402 + Rb
HM3887 + Rb
DRI319 + Rb
H1292 + Rb
BP13 + Rb
z Wild type strain of Tomato spotted wilt virus (TSWV)
y Strain of TSWV that has broken resistance to Sw5 gene.
0
2
4
6
8
10
12
14
16
18
20
TSW
V in
cid
ence
(%
)
mild moderate moderately severe severe
LSD (0.05) for total incidence = 11.557CV (%) = 93.333%
80
Table 4. Strains present in commercial variety trial, 2018 Fresno County.
Variety SW5 in
variety
Strain detected
Huron Five Points Merced
S6366 - Rb Rb Rb
UG19406 + Rb Rb Rb
BQ413 + Rb Rb Rb
UG16609 + Rb Rb Rb
HM5900 + Rb Rb Rb
H1293 + Rb Rb Rb
N6420 + Rb Rb Rb
BOS811 + Rb Rb Rb
AB311 + Rb Rb Rb
z Rb is in reference to the Sw5 resistance-breaking strain of Tomato spotted wilt virus (TSWV)
81
Monitoring and Abundance of Brown Marmorated Stink Bug in Peach and
Almond Orchards in the Northern San Joaquin Valley
Jhalendra Rijal1, Adriana Medina1, Roger Duncan1, Joanna Fisher2, and Frank Zalom2
1University of California Cooperative Extension, 3800 Cornucopia Way, Ste. A, Modesto, CA
95355; Phone: 209-525-6800; Email: [email protected] 2Department of Entomology, University of California-Davis, Davis, CA 95616
Introduction
Brown marmorated stink bug (BMSB), Halyomorpha halys, is a new invasive insect pest
of a variety of crops and has been causing serious economic losses in the United States since its
first detection in Pennsylvania in the early 2000s. In 2010, a significant crop loss ($37 million
only in apples) has been reported due to H. halys feeding in tree fruits such as peaches, apples
and other crops in the Mid-Atlantic region (Leskey et al. 2012), and since then, H. halys has
spread to over 44 U.S. states (www.stopbmsb.org). H. halys attacks a wide host range more than
170 plant species include crops, ornamental and landscape trees (www.stopbmsb.org). The major
host crops reported include apples, peaches, nectarines, pears, cherries, grapes, peppers,
tomatoes, sweet corn, beans, soybean, and more. Both immature (except the 1st instar) and adult
H. halys actively probe into fruiting structures (fruits and seed pods) by inserting their piercing-
sucking mouthparts, release the saliva, and uptake the content. H. halys is also considered as
nuisance as they move to houses en masses during the winter. H. halys overwinter in human-
made structures such as houses, barns, and remain active in the orchard throughout the season
after they emerge from the overwintering shelters in the Spring. H. halys remain active
throughout the season in finding and infesting crops and other plants. Almond, Prunus dulcis,
has recently been listed as a new host crop based on the finds of H. halys infestation in an
almond orchard in Modesto, California in 2017 (Rijal and Gyawaly 2018). Based on the
observations of the infested orchard and evaluations of developing fruits in 2017 and 2018, it is
clear that H. halys are capable of doing significant damage to almonds throughout the season.
Early season infestation (March-April) contributes to the nut abortion leading to the substantial
nut drop (more than 95% in late March-early April) while mid-to-late season feeding results in
damaged kernels based on the recent study (Rijal, Fisher, Zalom, unpublished data).
Although detected in 2002 in southern California (Lara et al. 2016), a large population of
H. halys was found in urban areas of Sacramento in the Fall-2013 (Ingels and Daane 2018) and
has since become a nuisance to the residents and businesses. Currently, there are 16 Counties
with the established H. halys population in residential areas
(https://cisr.ucr.edu/brown_marmorated_stinkbug.html). As the first reports, we documented the
finds of H. halys in crops – peaches in 2016 (Rijal and Duncan 2017), and almonds in 2017
(Rijal and Gyawaly 2018) in Stanislaus County. In order to understand the extent of the spread,
and potential damage caused by H. halys to peach and almond, we conducted trap-based H. halys
monitoring as well as fruit damage assessment studies in 2017-2018.
Materials and Methods
H. halys monitoring using traps. Two types of traps (pyramid and sticky panel) were
used to monitor H. halys activities in selected peach and almond orchards in both 2017 and 2018
seasons. Both types of the trap were baited with the H. halys lure (Trece Inc., Adair, OK). The
82
pyramid trap (Fig. 1A) is effective in catching both nymphs and adults, but this trap is expensive
and more cumbersome for field use. Therefore, along with other researchers working on H. halys
from other parts of the Country, we included the new trap type ‘sticky panel trap’ (Fig. 1B) in
addition to the pyramid trap. H. halys lure along with an insecticide strip (to contain trapped
insects) was placed inside a clear plastic container at the top of the pyramid trap (Fig. 1A). In
sticky trap, the sticky panel was stapled to the top of a wooden stake, and the lure was hung near
to the sticky panel by using a binder clip and a wire loop (Fig. 1B). Both traps were installed in
the ground are 4 ft. tall. 3-4 traps of each of the two types were used to monitor 7 (3 peach, 2
almond, 2 walnut) and 14 (7 peach, 7 almond) orchards in 2017 and 2018, respectively. Traps
were placed in between the trees in the border row, checked and cleaned them as needed. The
lure were changed at 4-week intervals in 2017, and at a 12-week interval (manufacturer’s
recommendation) in 2018. Due to the accumulation of dust and other debris, sticky traps were
changed at the interval of 4 weeks or less. Traps were placed in the Spring (April-May) through
the Fall (October-November).
H. halys damage to almonds. Based on the field observations and evaluations of the
developing fruits collected from the field and some controlled-cage studies conducted in 2017
and 2018, we summarized the nature of feeding damage by H. halys in almonds.
Results
H. halys monitoring using traps. In 2017 season monitoring, H. halys adults were
captured from three peach and two almond orchards along with the feeding damage in
developing fruits (Fig. 2). Although low in number, nymphs were present in one peach and two
almond orchard traps. H. halys adults were captured from the traps placed in two walnut
orchards. However, there was no indications of feeding damage to walnuts, and also no nymphal
activity was recorded in traps. As these are the first evidence of H. halys activities recorded in
commercial orchards in California, the overall population was low (the highest number of adult
captures was 64 adults from one peach orchard site). Although lacking a clear trend between
Fig. 1. H. halys monitoring traps, a) Pyramid trap, B) Sticky panel trap
83
sticky and pyramid traps in capturing H. halys population in these low-infested orchards, adults
were captured in both traps effectively (Fig. 2).
In 2018 season, H. halys adults were captured in traps from all seven peach orchards
(total seasonal number of adults: 30, 27, 12, 11, 23, 26 from 7 orchards) while nymphs were
captured from five out of those seven orchards. In almond orchards, H. halys adults were
captured from all seven orchards, but the number varied from low (total seasonal number of
adults: 1, 4, 6, 13, 14), moderate (total seasonal number of adults: 131), to high (seasonal total
number of adults: 729) infestation levels. 6 out of 7 orchards captured nymphs (maximum
number was 114 from the heavily infested block) in the trap. All of these peach and almond
orchards monitored were located in Stanislaus and Merced counties. In general, the sticky panel
captured more adults compared to the pyramid traps especially later part of the season
(September – November). In contrast, nymphal capture was higher in the pyramid than the sticky
panel trap. Seasonal phenology of H. halys capture in an almond orchard in the northern San
Joaquin Valley is shown in Fig. 3.
H. halys damage to almonds. H. halys feeding in almond in commercial orchard can
begin as early as mid-March when the overwintering adults start to move to the orchard and may
be present in the orchard throughout the season. However, early season feeding (from fruit set to
before shell hardening) seems to be severely impacted as adult feeding causes fruit abortion and
drop. Feeding by H. halys on developing fruits leads to the gumming nuts with multiple feeding
spots within the nut. The injury can be external (multiple gumming (Fig. 4A), light brown
speckles, yellowing) as well as internal (pinhole (Fig. 4B), water-soaked lesion, cork tissue (Fig.
4C), internal gumming). In 2018 season, we observed a substantial nut drop (with feeding injury)
in a few orchards in the northern San Joaquin Valley during April this year. The presence of
adults and the damage have been noticeably higher in the border tree rows next to the other host
trees such as ‘tree of heaven’ and potential overwintering shelters (e.g., houses, barns, wood
piles).
Fig. 2. Seasonal H. halys adult captures from 4 traps in seven orchards in Stanislaus
County, 2017
0
10
20
30
40
Tota
l se
asonal
H. hal
ys
adult
s ca
ptu
red Sticky Trap
84
In harvested almonds, multiple feeding spots (in many cases, in the form of distinct
necrotic spots) can be seen on the hull as well as in the shell (Fig. 5A). Depending on the time
and severity of the infestation, nutmeat (i.e., kernel) shows several types of injury (shriveled to
the completely damaged kernel, light to severe gumming, presence of multiple dark spots,
dimpled and deformed kernel) (Fig. 5B).
Some of the symptoms of H. halys damage resemble leaffooted and other stink bugs, but
the severity and timing of damage seem to be different. H. halys damage occurs as early as mid-
March and seems to continue for a few weeks to months, whereas leaffooted bug damage occurs
in a point of time (around mid-April in general). Since H. halys is a landscape-based pest, H.
halys can switch among different host crops within the season. H. halys are known to infest
orchards in great numbers, and therefore, the degree of damage can be high compared to the
leaffooted and other native stink bug damage. We also observed multiple feeding sites (up to 13
pinholes) within the nut and multiple numbers of injured nuts in a cluster within the branch, and
this H. halys feeding pattern is less common in the leaffooted bug infested nuts. Also, H. halys
feeding to the nuts showed necrotic spots in the kernels and presence of the multiple dark spots
(Fig. 5B).
Fig. 3. Seasonal phenology of H. halys activity in pyramid and sticky panel traps in
one of the almond orchards monitored in 2018 in Stanislaus County
0
0.05
0.1
0.15
0.2
0.25
0
0.3
0.6
0.9
1.2
1.5
No
. o
f n
ym
ph
s/tr
ap/n
igh
t
# a
du
lts/
trap
/wee
kSticky-adult
Pyramid-adult
Nymph (Pyramid+Sticky)
85
A B
C D
Fig. 4. H. halys feeding damage to developing almonds, A) External gumming, B) Pinhole
damage, C) Necrotic spots on the fruit, D) Necrotic feeding spots on kernel
Fig. 5. H. halys feeding damage to almonds showed up at harvest, A) hull and shell, B) kernel
A B
86
Conclusion
Brown marmorated stink bug has been spreading to crops in California and begun to
cause damage to commercial peach and almond orchards in the northern San Joaquin Valley. It is
critical that growers and pest control advisers (PCAs) pay close attention when monitoring fruit
orchards for H. halys presence and potential damage. Early monitoring is very important,
especially if the orchard is near to the areas with known infestations and areas with known tree
hosts such as the tree of heaven, Ailanthus altissima. Placement of a few sticky panel traps in the
border rows of the orchard beginning from March is recommended to detect H. halys activity and
infestation. Visual observations of insects (egg masses, nymphs, adults) and damaged fruit
(deformed fruits, fruits exuding gum) and beat tray sampling (shaking branches/twigs to dislodge
insects) are also useful in detecting the H. halys population. Although taking sample nuts from
the tree just before shaking can be a better strategy to see all injuries especially the external
gumming, it is not necessary as regular harvest sample works just fine. Hand crack the sample
nuts and carefully look for the feeding signs on the hull (external and internal), and the kernels
for the potential H. halys damage.
Literature Cited
Ingels, C.; Daane, K. Phenology of brown marmorated stink bug in a California urban
landscape. J. Econ. Entomol. 2018, 111, 780-786.
Lara, J.; Pickett, C.; Ingels, C.; Haviland, D.; Grafton-Cardwell E.; Doll, D.; James Bethke; Ben
Faber; S. Dara; and Mark Hoddle. Biological control program is being developed for
brown marmorated stink bug. California Agriculture, 2016, 70(1), 15-23.
Leskey, T.C.; Hamilton G.C.; Nielsen, A.L.; Polk, D.F.; Rodriguez-Saona C.; Bergh, J.C.;
Herbert, D.A. Pest status of the brown marmorated stink bug, Halyomorpha halys in the
USA. Outlooks Pest. Manage. 2012, 5, 218-226.
Rijal, J.P.; Duncan, R. First report of an established brown marmorated stink bug (Hemiptera:
Pentatomidae) population in California agricultural crops. J. Entomol. Sci. 2017, 53, 450-
454
Rijal, J.P.; and Gyawaly, S. Characterizing brown marmorated stink bug injury in almond, a new
host crop in California. Insects, 2018, 9(4), 126.
87
2019
Session #6
Managing Nitrogen Fertilizer Inputs
for Efficiency
Session Chair:
Eric Ellison
Steve Vasquez
88
Organic Soil Fertility for Organic Production of Leafy Green Vegetables
Richard Smith, UC Cooperative Extension, Vegetable Crop Farm Advisor, Monterey County
1432 Abbott St., Salinas, CA 93901 ([email protected]) 831-759-7357
Introduction
Organic production in Monterey County was worth 9% of total agricultural value, $390 million,
in 2017. Thirty years ago, organic vegetables were produced exclusively by small-scale growers
that sold to direct marketing outlets. While this scale of growing and marketing opportunity still
exists, large-scale vegetable producers now dominate the organic vegetable market and supply
mass markets across the US and Canada. This growth in the extent and scale of organic
production has focused greater attention on the need for more science-based information on
nutrient management, and in particular, nitrogen (N). In organic systems, N management is
complicated due to the forms of N fertilizers that are used, as well as the transformations of
complex forms of N to plant-available mineral nitrogen, ammonium and nitrate. The
decomposition of organic materials to produce nitrate is called mineralization, and is carried out
by soil microbes; the speed of this process depends on adequate temperature, moisture, and the
relative quantities of carbon (C) and N (C:N ratio) in the organic material.
In conventional vegetable production, growers have adopted tests for residual soil nitrate to
improve decisions on how much supplemental N fertilizer is needed for the crop. However, at
present, in organic production, little use of tests for residual soil nitrate are utilized by growers.
Given the complexity of the N cycle in organic vegetable production systems, there is a question
as to whether a test for residual soil nitrate would be a reliable indicator of the need for N
fertilizer.
This paper describes a project funded by the Fertilizer Research and Education Program
evaluating N fertilizer dynamics in organic cool season vegetable production on the Central
Coast of California.
Methods:
Twenty in-field nitrogen mineralization evaluations were conducted with cooperating growers in
commercial organic spinach, lettuce and broccoli production fields from 2016-18. Field sites
included diverse locations and soil types. Replicated unfertilized plots were established in each
field; within these plots sub areas with and without crop plants, as well as areas covered by
plastic mulch were established to determine the contribution of mineralization from the soil
organic matter without the confounding factors of crop removal of N and/or nitrate leaching from
irrigation. Soil temperatures and moisture at six inches deep were monitored in the soil using
Decagon 10HS sensors connected to a data logger. Unfertilized plots were paired with plots that
received the grower standard fertilizer program for comparison. Soil assays during the cropping
cycle included weekly evaluations of mineral N. Soils samples were collected at the beginning of
the cropping cycle for laboratory incubation studies conducted at UCD to determine N
mineralization. Also, initial soil samples were analyzed for total N, organic matter content, Olsen
phosphorus (P), total P and water extractable N and C. Crop yield and biomass N uptake was
evaluated at the end of the crop cycle (baby crops = app. 30 days and romaine and broccoli =
app. 65 – 70 days).
89
In-field evaluations of N and P release from dry organic fertilizers were conducted to determine
the rate and quantity of N released. Materials evaluated included 4-4-2 (a mix of chicken
manure, and meat and bone meals) and 12-0-0 (feather meal). Twenty grams of oven-dry
material were placed in propylene mesh bags and placed on top of the soil or buried three inches
deep to simulate a top dress or soil-incorporated fertilizer application, respectively. Replicated
samples of the bags were collected weekly and weighed and analyzed for N, P and potassium
(K). In addition, laboratory incubations to determine N mineralization of dry and liquid
fertilizers were conducted at UCD under controlled conditions.
The amount of irrigation water that was applied during the cropping cycle was measured by
installing three funnels connected to a PVC pipe reservoir. The quantity of water in the reservoir
was measured each week to determine sprinkler applied water. In fields with drip irrigation a
flow meter was installed on a drip line that extended the length of the field. The nitrate content of
the water was measured to determine the load of N applied in the irrigation water. All N inputs
from fertilizer and residual soil mineral N were calculated for each plot.
Results:
The quantity of N mineralized from soil organic matter in the 20 evaluations ranged from 0.3 to
2.8 lbs N/A/day with an average of 1.7 lbs N/A/day. Laboratory evaluations of soil
mineralization ranged from 0.3 to 1.9 lbs N/A/day with an average of 0.6 lbs N/A/day. The yield
of the vegetables in these fields was improved by the addition of fertilizer in 17 out of 20
evaluations, indicating that mineralization of N from soil organic matter was insufficient in most
fields to achieve maximum yield. This may be explained by the high demand for N over a short
period of time during the crop cycle for crops like spinach and lettuce. For instance, in spinach
during the first two weeks of the crop cycle when the crop is germinating and getting established,
it takes up only 7-10 lbs of N/A. However, during the next two weeks until harvest, spinach takes
up as much as 5 lbs N/A/day. Likewise, during the first 30 days of the lettuce crop cycle, total N
uptake is 15 lbs N/A, but during the next 5 weeks until harvest, N uptake is 3.6 lbs N/A/day. This
high rate of N demand probably explains why maximum yield cannot normally be achieved in
these crops with mineralization of N from soil organic matter alone.
Given that soil-building practices alone do not appear to be able to achieve maximum yield, it is
clear that fertilizer N is essential to successful leafy green vegetable production. Are there ways
to improve N use efficiency? Total crop N uptake provides a starting point on how much N to
apply to a crop (Table 1). In conventional production measuring residual soil nitrate prior to the
first fertilizer application helps fine tune how much fertilizer N is needed. That same concept
may be applicable in organic production. However, there are two issues for fast growing leafy
vegetables, 1) their short crop cycle, and 2) the time it takes for nitrate-N to be released from
organic fertilizers. For these crops, the only time that you can react to measurements of residual
soil nitrate is prior to planting or very early in the crop cycle because later in the crop cycle there
is not enough time for the organic fertilizer to release nitrate-N.
The predictive value of preplant soil nitrate measurements can be limited if significant leaching
occurs due to with the water used to germinate the crop and measuring residual soil nitrate after
the germination phase of the crop could improve the estimates of available residual soil nitrate.
90
However, the fast crop cycle of the baby vegetables and slow rate of release of organic
fertilizers, necessitates making fertilizer decisions early in the crop cycle and measurements of
residual soil nitrate are the best measure that we have for adjusting fertilizer applications. For
instance, in a 2018 trial in spinach with 25 ppm nitrate-N on a clay loam soil prior to planting,
reducing the preplant application of 4-4-2 from 2000 lbs to 1000 lbs/A did not reduce yield. In
the Central Coast production fields, 2nd or 3rd crops of the season can often have high quantities
of residual soil nitrate which provides opportunities for growers to measure soil nitrate and adjust
fertilizer applications accordingly.
In 2016 and 2017, evaluations of the release of N from 4-4-2 and 12-0-0 were conducted. The
average percent of N released from 4-4-2 over the two years was 62.1% for material buried in the
soil and 42.2% for surface application (Table 2). The difference between surface vs buried
applications was more exaggerated for 12-0-0 with 31.5 and 86.0% of the N released,
respectively. The release of N from organic fertilizers follows a typical pattern with initial rapid
release of N followed by a slow, steady release that extends over a long period of time.
Incorporating the fertilizers into the soil increases the initial rate of N release; fertilizer with a
higher N concentration showed faster N release. Laboratory evaluation showed a 20-30% lower
rate of N release of 4-4-2 and 12-0-0 over the same period of time (Table 3). The N release from
fertilizer may have implications for organic operations subject to water quality regulations. For
instance, growers applied from 1.2 to 4.8 times more N than the crop took up in 20 evaluations.
However, discounting the amount of N that mineralized from the organic fertilizer, organic
fertilizer applications in this survey ranged from 0.4 to 2.7 times crop N uptake.
The fate of N from organic fertilizers that is not released during the crop cycle is not well
understood. Presumably it becomes available to future crops, mineralizing at a slow, steady rate
similar to soil organic matter. The high usage of 4-4-2 which is a mix of chicken manure
blended with meat and bone meal on larger-scale organic farms brings the benefits of adding
significant amounts of organic matter to ranches that may not have extensive cover crop or
compost programs. For instance, 2-3,000 lbs 4-4-2 per crop 2-3 times per season adds 2-4.5 tons
of carbon-rich organic matter to the soil which may serve as the main soil building practice in
these intensive production systems.
Soil P values at each survey site were relatively modest for the Salinas Valley vegetable ground,
except for one that was located on an old dairy. Bicarbonate extractable P values ranged from 10
to 57 ppm with a mean of 37 ppm on the non-dairy sites (Table 4). The moderate P values
occurred in spite of the common usage of 4-4-2 which has a ratio of 1:1 of N:P2O5. Interestingly,
we did not observe higher levels of total P organic farms than on conventional. The form of P in
4-4-2 fertilizer comes mostly from bone meal, which is not soluble at soil pH greater than 7.0; all
survey sites had pH above 7.0, meaning that bone meal is a highly inefficient P source in this
production system.
Many of the concepts described here are for fast-growing leafy green vegetables. They may not
apply to longer-season crops that are deeper rooted and can scavenge N from deeper in the soil
profile. Measurements of residual soil nitrate provide the greatest opportunity for fine tuning soil
fertilizer programs for these fast-growing, high N demanding crops.
91
Table 1. Typical macronutrient uptake and harvest removal of cool season vegetables
Seasonal crop uptake (lb/acre) % nutrient removal
Crop N P K with harvest
broccoli 250-350 40-50 280-380 25-35
Brussels sprouts 350-500 40-60 300-500 30-50
cauliflower 250-300 40-45 250-300 25-35
celery 200-300 40-60 300-500 50-65
head or romaine lettuce 120-160 12-16 150-200 50-60
baby lettuce 60-70 5-7 80-100 65-75
spinach 90-130 12-18 150-200 65-75
Adapted from Hartz, in press
Table 2. Percent of N released from 4-4-2 in surface and buried applications in 2016 and 2017;
Measurement of N release from 12-0-0 from surface and buried applications in 2017
2016 2017
4-4-2 4-4-2 12-0-0
Days Surface Buried Days Surface Buried Surface Buried
0 0 0 0 0 0.0 0.0 0
10 30 50 7 24 30 13 31
18 31 61 15 26 46 12 59
25 36 65 22 25 50 12 75
31 34 64 28 33 51 15 79
38 42 66 36 35 51 14 82
44 45 68 42 33 51 17 84
52 47 69 51 34 52 26 84
60 50 66 55 36 54 32 86
63 48 70 --- --- --- --- ---
Table 3. Estimates of percent of N release from various
organic fertilizers in laboratory incubations conducted at 68 °F.
Material 2 weeks 4 weeks 8 weeks
2.5-2.0-2.5 4 6 14
4-4-2 29 31 38
8-5-1 47 44 59
10-5-2 44 49 59
12-0-0 49 57 59
92
Table 4. Average of 20 pairs of conventional and organic fields1
Soil Constituent Conventional Organic
Organic Matter % 2.0 2.1
Total Nitrogen % 0.12 0.12
Total Carbon % 1.01 1.03
Phosphorous (Olsen) ppm 37 42
Phosphorous (Total) ppm 0.10 0.09
1 – Fields were paired for the same crop and soil type.
93
Field Evaluation and Demonstration of Controlled Release N Fertilizers
in the Western United States
Project Leaders:
Charles A. Sanchez, Professor, University of Arizona, Maricopa
Agricultural Center, 37860 W Smith Enke Rd, Maricopa, AZ
85138, phone 928-941-2090, e-mail [email protected]
Richard Smith, Farm Advisor, Cooperative Extension Monterey County, 1432 Abbott Street,
Salinas, CA 93901, phone 831-759-7357, e-mail
INTRODUCTION
Intensive vegetable production in the southwestern U.S. receives large annual applications of
nitrogen (N) fertilizers. Amounts of N applied range from 200 to 400 kg/ha and crop recoveries
are generally less than 50% (Mosier et al., 2004). There are numerous possible fates of fertilizer
applied N in addition to the desired outcome of crop uptake (Sanchez and Dorege, 1996; Havlin
et al., 2005). The urea and ammonium components of the N fertilizer might be lost through
ammonia volatilization. The nitrate-N might be lost to leaching with irrigation water below the
crop root zone possibly impairing surface and ground water (Sanchez, 2000). Nitrate might also
be lost as N2 and N2O gasses via de-nitrification processes affecting air quality and climate.
Furthermore, all forms of N might be immobilized into the organic soil fraction by the soil
microbial population where availability to the crop is delayed. The global warming potential of
N2O is 300 times that of CO2 and N fertilizer is estimated to account for one-third the total
greenhouse gas production in agriculture (Strange et al., 2008). One study reported that N
fertilization (inorganic or organic) accounted for 75% of the greenhouse gas emissions from
agriculture production (including production, application, and nitrous oxide emissions) and after
N is accounted for there are no significant differences between conventional, organic, or integrated
farming practices (Hiller et al., 2009).
N management in the western United States remains a continuing challenge. Both California and
Arizona have mandated Best Management Practices (BMP’s) to varying degrees. These practices
generally involve timing, amounts, and placement of N, and irrigation water application. The use
of controlled release N (CRN) fertilizer sources is another promising option. The successful
implementation of CRN management where appropriate will reduce adverse environmental
impacts of fertilizer N and improve profitability in California and the western United States in
general.
OBJECTIVES
The objectives of this project are to conduct experiment-demonstrations with CRN technologies
in vegetable producing areas in Arizona California with a wide range of CRN technologies
available. Experiment demonstrations will all occur with grower-cooperators and CRN
management will be compared to their standard practices. Success will be discerned by data
collected, grower interest, and grower implementation.
94
DESCRIPTION
We have determined release rates and we modeled release for a number of CRN products in our
possession. This included ESN, and various Duration, Polyon, and GalXe products. We are
using these data collected on release rates to guide our product selections for each crop planting
window.
Experiment demonstrations
have been conducted and
are on-going in the desert
and central coast
production regions.
Studies in the desert have
been conducted with
grower cooperators in Pinal
and Yuma counties
Arizona and Imperial and
Riverside Counties
California. Studies in the
central coast have been in
Monterey County. Rate and methods of application of CRN management gave been compared to
the grower standard N management (Figure 1). Crops evaluated include iceberg, romaine, and
baby lettuce, broccoli, cauliflower, spinach, watermelons, tomatoes, peppers, and onions. In all
experiment-demonstrations the crop N
status was monitored with N tissue and
soil testing. Marketable yields were
collected at harvest in all experiment-
demonstrations.
RESULTS AND DISCUSION
There have been variation in results
depending on crop-site-season. The
results for spinach to CRN 45 in winter
2015 are shown in Tables 1. These
observed improvements yield responses
of spinach to CRN management are
typical of results we observe for spinach
over several studies conducted in 2015
through 2017. Lettuce and broccoli have
also shown positive responses to CRN
management for many site-seasons
(Tables 2 and 3 show some results for lettuce and broccoli). However, there are risks of crop
damage to when using one of the faster release products (CRN 90) in warm fall season (data not
shown).
Figure 2. Various fertilizer application methods in experiment-demonstrations.
95
TAKE HOME MESSAGE
Overall, the data show that CRN management has promise as a tool for efficient N management
in vegetable cropping systems in the western United States. In some instances we observed
increased growth and yield compared to GSP. In many cases production is maximized at lower
N rates. There are risks of damage when CRN 90 is used in warm falls. The solution would be
using CRN120 or band placement. Many growers have incorporated CRN into their
management programs.
Table 2. Response of spinach to N rate and N
source. N Rate N Source Yield
(MT/ha) Soil NH4-N
(mg/kg) Soil Nitrate-N (mg/kg)
Leaf N (%) N Uptake (kg/ha)
0 --- 2.2 3.4 3.6 3.29 5.11 150 CRN 45 9.5 2.8 7.1 2.84 27.2 300 CRN 45 12.8 8.2 27.2 4.28 38.7 150 AS 9.5 1.2 7.5 4.25 27.8 300 AS 8.7 2.3 30.0 4.76 28.5 150 FUSN 9.3 4.2 4.4 4.19 27.1 300 FUSN 9.9 2.1 13.9 4.33 28.7 150 Urea 9.6 2.3 7.2 4.12 27.7 300 Urea 8.8 1.6 8.9 4.10 25.2 150 SU 8.0 2.9 5.4 4.50 24.7 300 SU 9.9 5.1 5.8 4.60 31.9
Stat. N Rate L** Q** NS L** L*Q* L**Q** N Source 1.8 3.2 9.8 0.40 NS
96
LITERATURE CITED
Havlin, J., S., L. Tisdale, J. D. Beaton, and W.L. Nelson. 2005. – Soil Fertility and Fertilizers, 7th
Edition. Pearson Prentice Hall, NJ.
Hiller, J., C. Hawes, G. R. Squire, A. Hilton, S. Wale, and P. Smith. 2009. The carbon foot
prints of food production. International. J. Agric. Sustain. 7:107-118.
Mosier, A. R, Syers, J. K., and Freney, J. R. 2004. Nitrogen fertilizer: An essential component of
increased food, feed, and fiber production. Pages 3-18 in: SCOPE 65: Agriculture and the
Nitrogen Cycle: Assessing the Impacts of Fertilizer Use on Food Production and the
Environment, A. R. Mosier, J. K. Syers, and J. R. Freney, eds. Island Press, Washington,
DC.
Sanchez, CA. 2000. Response of lettuce to water and N on sand and the potential for leaching of
nitrate-N. HortScience 35:73-77.
Sanchez, C. A., and T. A. Doerge. 1999. Using nutrient uptake patterns to develop efficient
nitrogen management strategies for vegetables. HortTechnology 9:601-606.
Strange, A., J. Park, R. Bennett, and R. Phipps. 2008. The use of life cycle assessment to
evaluate the environmental impacts of growing genetically modified nitrogen use
efficient canola. Plant Biotechnology J. 6:337-345.
ACKNOWLEDGMENTS
We gratefully acknowledge support of the FREP program for sponsoring this work, the fertilizer
companies that provided products including Koch Industries, JR Simplot, and Agrium. We also
appreciate the cooperation of participating growers.
97
Evaluating HFLC Nitrogen Management Strategies to Minimize Reactive
Nitrogen Mobilization from California Almond Orchards
Ouaknin Hanna1, Patrick K. Nichols2, Christine M. Stockert3, Sat Darshan S. Khalsa3, Patrick H.
Brown3, David R. Smart2, Thomas Harter1
1. Department of Land, Air & Water Resources, UC Davis, Davis CA 95616.
2. Department of Viticulture and Enology, UC Davis, Davis, CA 95616.
3. Department of Plant Sciences, UC Davis, Davis CA 95616.
Introduction
Nitrogen (N) is the most important agricultural nutrient for crop yield. Fertilizer N (ammonium
(NH+4) and nitrate (NO-
3) is the key nitrogen source for crops. Excess N leads to emissions of
greenhouse gases as nitrous oxide (N2O) and leaching of NO-3 to groundwater. Nitrate pollution
of groundwater, commonly used as source of drinking water, induced new policies and regulations
in California known as the Irrigated Lands Regulatory Program (ILRP). The program oversees
“waste discharge” to groundwater, including NO-3 leaching from agriculture. The new regulations
mandate that growers implement N management plans and improve the balance between field N
inputs with harvested N (outputs), thus reducing N loading to groundwater. One management
strategy to achieve better nitrogen use efficiency (NUE) is high frequency low concentration
(HFLC) fertigation where N fertilizer is split applied in multiple low concentration doses
throughout the growing season.
The practice of applying fertilizer through the irrigation system (fertigation) has been used since
1954 and was combined with drip irrigation in 1974 in bell pepper (Incrocci et al., 2017). Around
the world, fertigation has become common practice over the past 60 years in many crops (Kafkafi,
2005). Fertigation provides the flexibility of applying the fertilizer in split applications, thereby
meeting crop demand using multiple low doses that plants can utilize efficiently. The doses should
be adjusted to soil type, crop type and climate. HFLC has been shown to increase water and
nutrient use efficiency (NUE), by supplying water and nutrients to match demand during critical
physiological stages of growth (Silber et al., 2003).
HFLC has been tested in different vegetable crops at various fertigation frequencies with consistent
results. Higher N uptake and NUE was demonstrated in multiple crops including lettuce (Silber et
al., 2003), tomatoes (Farneselli et al., 2015), onions (Rajput and Patel, 2006) and potatoes (Badr
and Taalab, 2011). In some studies, a reduction in NO3 concentration in the root zone (Badr and
Taalab, 2011; Rajput and Patel, 2006; Farneselli et al., 2015) and NO3 leaching (Kurtzman
etal.,2013) was reported. The frequency of fertigation ranged from daily in lettuce (Silber et al.,
2003) up to every 30 minutes in bell peppers (Silber et al., 2005).
There are fewer HFLC studies in orchards. Most of the studies test splitting fertigation into 4 or 5
events during the growing season (Worleyl et al., 1995; Yin et al., 2009). In pecan, four
applications of 25 lb N/acre each (100 in total) was compared to one broadcast fertilization (of 200
lb N/acre) for 10 years (Worleyl et al., 1995). The results of the study showed no effect on yield
and quality while N amounts can be reduced. In pear, splitting fertigation into five applications
compared to one application increased NUE and allowed the reduction of fertilizer by 20% (Yin
et al., 2009). In a citrus orchard, application of monthly drip fertigation resulted in improved NUE
and lower NO3−concentrations in the soil profile compared to the low frequency high N flood
irrigation (Quiñones et al., 2007). In another citrus study, Thompson et al. (2001) showed higher
leaf N and lower NO3 leaching under weekly fertigation compared to 3 times a year fertigation.
98
Syvertsen and Jifon (2001) found no differences in leaf N concentration, canopy size or fruit yield
between 12, 37 and 80 split fertigations. Furthermore, they found no reduction in NO-3 leaching
when increasing the frequency to 80. However, the rate of fertilizer in this study was twice the
amount of the other studies (Thompson et al., 2001; Quiñones et al., 2007). The work clearly
demonstrated that splitting fertigation alone does not yield improvements in leaching when N
applications are not closely matched with uptake. Therefore, when applying high load of nitrogen,
splitting fertigation won’t create the desired effect of improving NUE and lowering leaching.
Almonds are the second most valuable crop after grapes with over one million acres in California
(CDFA 2018). According to a 2007 survey, 81% of growers use fertigation and 65% use three or
more split application of N fertilizer as a best management practice (Lopus et al., 2010). A recent
study in California almond compared HFLC fertigation to the more commonly practiced triple
split application ("BMP", Baram et al., 2016) and showed a 20% improvement in NUE with HFLC,
which presumably led to fewer atmospheric losses of N2O and less NO3 leaching.
The aim of this study is to provide economically viable solutions to improve N fertilizer and water
use efficiencies in almond orchards that also meet emerging regulations outlined in Central Valley
ILRP and under California’s 2030 greenhouse gas emission (GHG) targets. Specific objectives
include 1) assess annual GHG emissions (N2O, CH4 and CO2) at the orchard scale under HFLC
management; 2) measure the recharge rate and NO3− movement below the root zone; 3) determine
groundwater quality impacts and their spatio-temporal dynamics using conventional regulatory
groundwater monitoring programs and; 4) determine NO3− discharge to groundwater from the
orchard.
Methods
Study site: The site a commercial almond orchard located in Modesto CA, north of the Tuolumne
River, east of the San Joaquin River, and west of Modesto. The site is located above a phreatic
aquifer with the water table at about 7 m depth. Surrounding land use includes mostly almond and
walnut orchards. No dairy farms are located upgradient of the property along the groundwater
flowpath. The 130-acre orchard consists of four blocks. Tree age varies by block (blocks 1, 3 – 17
years and blocks 2,4 – 8 years). The orchard is planted with four varieties: ‘Nonpareil’, ‘Aldrich’,
‘Carmel’ and ‘Fritz’. The orchard is irrigated using 4 different irrigation methods (microsprinkler,
drip, buried-line microsprinkler, double line microsprinkler)
Fertigation: During 2018 growing season fertigation was split into14 applications totalling 257
kg-N/ha (230 lbs-N/acre). The source of fertigation changed each month: CAN17(Feb), metagrow
27-0-0-5(March), UAN32 (April), metagrow8-4-10 (May). Each fertigation received 2 to 16 kg
N/ha (2 to 15 lbs-N/acre) (dependent on the source). During the rainy season, February and March,
a minimal amount of water was used to apply fertilizer. The fertigation was assisted by a
computerized system (“pH Technologies”) to ease the logistics of high frequency fertigation
feeding in the orchard. Due to system restrictions, two blocks are fertigated at a time, either the
eastern two blocks or the western two blocks. The fertilizer was injected toward the end of the
irrigation event (Baram et al., 2016). NUE was calculated as the ratio of tree uptake (N mass in
woody mass, kernel, shell and hull) and the applied N. The difference between applied N and
uptake was assumed to equal the sum of N in the root zone, NO3 leaching to groundwater, N2O
emissions, and other gaseous losses. Runoff losses are negligible.
Monitoring and instrumentation: The site combines several tiers to measure the fate of N: a. field-
scale mass balance including measurements of N2O emissions; b. continuous monitoring of root
zone water and N using an intensive vadose zone monitoring network installed at 3 m depth (Harter
99
et al., 2005, Botros et al., 2009, Baram et al., 2016); and c. monitoring first encountered
groundwater for NO3- to determine actual discharge to groundwater (e.g., Harter et al., 2002,
2014).
Measurements of Mass Balance and N2O emissions: Mass balance estimates are made based on
measurements of N applied, N harvested, and N2O emission. N applied in fertigation was
occasionally sampled from the emitters during fertigation and the total N amount was calculated
based on the computerized system. Yields were reported by the grower and harvested N was
measured from grinding and analyzing sub samples collected during harvest (Muhammad et al.,
2015). N2O emission samples were collected weekly by the static chamber method and analyzed
on a gas chromatograph (Parkin and Venterea, 2010). Chamber collars were installed in the four
blocks (experimental units) in the orchard with three subsample transects in each block measuring
in 5 distances from the row (0, 50, 100, 150, 200 cm). Additionally, soil temperature and moisture
level was measured and soil samples were collected for chemical analysis.
Monitoring the fate of 𝑁𝑂3− in the root zone: Seven locations were equipped with two arrays of
soil water and N monitoring equipment: solution samplers at approximately 30 cm, 60 cm, 90 cm,
180 cm, 300 cm (1,2,3,6,10 ft), as well as 4 tensiometers, two each at depths of 280 cm and 300
cm. Construction and installation of equipment followed procedures outlined in Baram et al., 2016.
Soil water samples were collected from porous cup solution samplers once a week after each
fertigation to measure NO3− and NH4
+ throughout the soil profile at the specified depths.
Tensiometers recorded soil matric potential every 15 min, using dataloggers (CR1000 by Campbell
sci.). Additionally, a neutron probe was used at each sampling event to monitor soil moisture to 3
m depth throughout the growing season.
Groundwater monitoring: In 2017, a shallow groundwater monitoring well network of 20 wells
was completed. Beginning in the fall 2018 and continuing over the remainder of the project, regular
groundwater sampling is collected and measured for NO3−,NH4
+ and salinity. Initial measurements
are twice per quarter through July 2019, then once per quarter over the next 5 years. Once a year,
samples are analyzed for all major constituents.
Results and Discussion
This report outlines one growing season with BMP (2017) and one year of HFLC treatment (2018).
To evaluate the full impact of the HFLC fertigation on groundwater discharge the project will
continue for at least an additional 3 years. The dynamics of N (NO3− and NH4
+) in the root zone,
the deep vadose zone, ground water and N2O emissions for the first year of HFLC treatment in
this intensely monitored almond orchard are presented herein.
The annual average N from the seven sites, across the growing season, as either NH4+ or NO3
− in
the root zone was high (Figure 1). Along the soil profile, the average mass of or NO3− ranged from
4.5 to 10 kg-N/ha/ft. The total mass in the first 300 cm (~10ft) was 172 kg-N/ha and 10 kg-N/ha
(153 and 8.9 lbs-N/acre) of NO3- and NH4 respectively. These high concentrations, especially
below the effective root zone at 180 cm and 280 cm depth are susceptible to leaching (Kurtzman
et al., 2013). The annual dynamic of N mass in the root zone show decreasing concentrations,
especially in the upper profile, during the winter and increased concentrations during the summer.
This provides indirect evidence of N leaching.
100
Figure 1: NH4 and NO3
- mass in the upper 300 cm (~10ft) of the soil profile. Measured from
porewater samplers
Cumulative fluxes out of the root zone at 300 cm (~10ft) depth from each site were calculated
from tensiometer readings (Figure 2). There is a consistent increase from April to July in both the
water flux and NO3, which plateaus around July, depending on the site. During July and August,
there was no irrigation in the orchard, and daytime temperatures rose to between 80 – 90oF. Dry
conditions during this period limited N movement similar to the results reported by Baram et al.,
2016. The movement of NO3- out of the root zone (Figure 2) fits the changing concentrations in
the groundwater at the closest well to each site (Figure 3). Sites 3 and 4 show similar trends of
increase in the flux, followed by increase in the NO3- concentrations in the well. The increase at
site 3 is more moderate than at site 4. The results are thought to indicate the vulnerability of nitrate
movement in the soil, similar perhaps this year to previous years, but not the direct impact of this
year’s fertigation – travel time to the water table are too long for that to occur. Site 2 show a
decrease in flux and a decrease in the concentration of NO3-. Site 6 is mostly sandy, and the
leaching out of this site is too fast for the tensiometers to record, or the water is bypassing the
tensiometers as suggested by Baram et al., 2016 and Hillel, 1998.
Figure 2: cumulative fluxes of water (A) and NO3 (B) out of the root zone at each of the monitoring
sites
At the beginning of the trial in October 2017, groundwater nitrate concentrations ranged from 4.5
mg/l NO3-N in the east row up to 56.9 mg/l NO3-N in the middle of the field (Table 1). Near the
end of fertigation in May, NO3- concentrations increased in the groundwater in 8 of the 20 wells.
When irrigation ceased between July and mid-November in preparation and during harvest, NO3-
concentrations in the monitoring wells didn’t change indicating little movement of NO3 to the
groundwater.
101
Figure 3: NO3 concentrations in the MW closest to each of the monitoring sites
Five sets of groundwater nitrate-N data were collected so far. While we observe some significant
temporal variability, spatial variability between wells is overall larger than the variability over
time, at individual wells. Some patterns emerge. Fifteen of the twenty monitoring wells,
consistently exceed 10 mg N/L, the maximum contamination level for nitrate in drinking water.
The lowest concentrations are observed in three wells in the northeast corner (MWs 1, 2, and 3).
These wells represent groundwater that has been recharged mostly upgradient of the orchard,
where a vineyard used to be located that was replaced with a new almond orchard, about three
years ago. It is expected that the concentrations in these three MW may increase with time due to
the higher nitrogen inputs in the adjacent new almond orchard when compared to the previous use
as vineyard. This upgradient property is outside this project’s management zone.
Table 1: Nitrate-N (mg/L) measured in the 20 MW at the almond orchard over time
MW 1 2 3 4 5 6 7 8 9 1
0
1
1
1
2
1
3
1
4 15 16
1
7
1
8
1
9
2
0
Oct-
17
4.
5 6
9.
7
2
5
1
6
18.
3
1
9
2
3 6.8
1
7
2
3
2
7
5
7
3
1
42.
6
20.
8
3
4
1
6
8.
4
2
7
May-
18
4.
7
3.
5
1
0
3
3
2
1
23.
9
2
1
1
1 5.5
1
7
2
2
2
5
4
9
3
7
55.
9
20.
3
2
6
1
9
1
9
2
0
Jul-
18
1
3
9.
5
1
0
3
7
1
9
19.
7
1
9
2
6 6.7
1
7
2
3
2
9
5
6
3
2
53.
7
26.
4
3
2
2
3
1
8
3
6
Sep-
18
1
3
1
1
1
0
3
5
1
8
18.
5
1
9
2
5 6.5
1
7
2
2
2
8
6
0
3
1
50.
5
25.
9
3
2
2
4
1
7
3
3
Nov-
18
1
1
9.
4
1
0
3
9
1
7
17.
3
1
8
2
8
6.0
4
1
6
2
1
2
7
6
0
3
0
50.
7
26.
2
3
2
2
4
1
7
3
4
To create a more complete picture of the nitrogen mass balance, N2O emissions were collected.
Cumulative emissions from each of the four blocks in the orchard show a seasonal pattern of
cumulative emissions, where the peak of emissions are during spring, similar to observations by
Shellenberg et al. (2012) in a California almond orchard. This is likely attributable to the increasing
temperatures while the soil is still moist from winter/spring rain and fertilizer quantities are
generally increased for the bloom. Alsina et al. (2013) did find a significant correlation between
N2O emission and water filled pore space, however their observations were statistically
independent of temperature. The results show cumulative emissions of around 50 to 400 g N2O-
N/ha (0.04-0.3 lbs-N/acre), in drip and microsprinklers irrigation respectively. This supports meta-
analysis results from Cayuela et al., (2017) which showed a 44% lower N2O emission factor in
drip irrigation compared to sprinkler irrigation in Mediterranean cropping systems. However,
Alsina et al., (2013) observed greater N2O emissions in drip irrigated orchard compared to
102
sprinkler irrigated, which was also observed in a drip irrigated block with compost applications
relative to two sprinkler irrigated blocks.
A two-year field trial in a Madera almond orchard (2015-2016) showed significantly lower N2O
emissions under HFLC compared to two other fertigation management strategies (Nichols,
unpublished data). Wolff et al. (2017) observed greater emissions from high frequency fertilizer
application compared to standard orchard fertilizer practice, but only when UAN was the only
fertilizer type. Wolff et al., (2017) observed decreased emissions when the high frequency
applications used nitrate with calcium and potassium. Thus far, N2O emissions have proven
difficult to generalize and show site specific dynamics based of biogeochemical soil parameter and
climate.
Conclusions
From a management perspective, the challenge before us is to reduce N losses from the root zone
as much as possible, ideally to the point where nitrate-N levels in the shallow groundwater are less
than the drinking water limit of 10 mg N/L. If winter recharge is maintained in the 15 – 30 cm/yr
(0.5-1 ft/year) range, this would require us to reduce N losses from the root zone (after any
denitrification) at least two-fold. We anticipate that improved management practices begun this
year will take several years to fully affect monitoring well data.
HFLC management for 2018 resulted NUE of 0.78, which is similar to other reported values in
almonds. Further management changes will be considered to fine-tune applied N in the next
growing season.
Acknowledgments: Funding for this work has been provided by the Almond Board of California.
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related N2O and CH4emissions during fertigation in a California almond orchard.
Ecosphere 4(1): 1–21. doi: 10.1890/ES12-00236.1.
Badr, M.A., and A.S. Taalab. 2011. Nitrogen Application Rate and Fertigation Frequency for
Drip-irrigated Potato. 5(7): 817–825.
Baram, S., V. Couvreur, T. Harter, M. Read, P.H. Brown, et al. 2016. Assessment of orchard N
losses to groundwater with a vadose zone monitoring network. Agric. Water Manag.
172(3): 83–95. doi: 10.1016/j.agwat.2016.04.012.
Cayuela, M.L., E. Aguilera, A. Sanz-Cobena, D.C. Adams, D. Abalos, et al. 2017. Direct nitrous
oxide emissions in Mediterranean climate cropping systems: Emission factors based on a
meta-analysis of available measurement data. Agric. Ecosyst. Environ. 238: 25–35. doi:
10.1016/j.agee.2016.10.006.
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frequency improves nitrogen uptake and crop performance in processing tomato grown with
high nitrogen and water supply. Agric. Water Manag. 154: 52–58. doi:
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Incrocci, L., D. Massa, and A. Pardossi. 2017. New Trends in the Fertigation Management of
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Kafkafi, U. 2005. Global Aspects of Fertigation Usage. Fert. Proc. Sel. Pap. IPI-NATESC-CAU-
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Lopus, S.E., M.P. Santib��ez, R.H. Beede, R.A. Duncan, J. Edstrom, et al. 2010. Survey
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Muhammad, S., B.L. Sanden, B.D. Lampinen, S. Saa, M.I. Siddiqui, et al. 2015. Seasonal
changes in nutrient content and concentrations in a mature deciduous tree species : Studies
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Affect Citrus Tree Growth , Fruit Yield , Nitrogen Uptake , and Leaching Losses. Proc.
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Wolff, M.W., J.W. Hopmans, C.M. Stockert, M. Burger, B.L. Sanden, et al. 2017. Effects of drip
fertigation frequency and N-source on soil N2O production in almonds. Agric. Ecosyst.
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104
2019
Session #7
IPM: Weeds
Session Chairs:
Jeff Dahlberg
Karen Lowell
105
Understanding the Biology of Alkaliweed (Cressa truxillensis) so Control
Strategies can be Developed in Pistachios
Kurt Hembree, Farm Advisor, UC Cooperative Extension, Fresno County; 550 E. Shaw Ave.
Suite 210-B, Fresno, CA 93710. Phone (559) 241-7520, [email protected]
James Schaeffer, SRA, University of California Cooperative Extension, Fresno County; 550 E.
Shaw Ave. Suite 210-B, Fresno, CA 93710. Phone (559) 241-7520, [email protected]
Keywords: alkaliweed, pistachios, saline or alkaline soils, growth characteristics
Abstract
Alkaliweed (Cressa truxillensis) is a California native plant species that has been reported in
seven other U.S. states. Recently, it has become a problematic weed in several southern San
Joaquin Valley sites, including open ground, irrigation canals and ditches, roadsides and
pistachio orchards. Thus far, alkaliweed has been reported invading young pistachio orchards in
Madera, Fresno, Kings and Kern counties. Alkaliweed is a perennial plant and member of the
Convolvulaceae, or morningglory, family and is disseminated both by seed and roots. It also
appears to be associated with saline or alkaline soils, but this has not been confirmed. To date, no
information has been published on the biology attributes or response to chemical and non-
chemical control measures of alkaliweed, particularly as it applies to growth in pistachios.
Therefore, in order to develop effective chemical, physical and cultural control options for this
weed in pistachios, field, greenhouse, and laboratory studies are underway to better understand
specific growth characteristics. Studies being looked at include shade, moisture and salinity
tolerance, seed germination and dormancy requirements, shoot and root growth characteristics
and physical response to pre- and postemergence herbicides. Additionally, a regional
geographical information system (GIS) analysis is being conducted to better understand its
distribution within the region and any similarities as related to soil salinity, location to irrigation
canals/ditches and other similarities.
106
Weedy Rice in California: what makes a pest a pest?
Whitney Brim-DeForest, CE Rice Advisor, UCCE Sutter-Yuba,
142A Garden Hwy, Yuba City, CA 95991
Phone (530) 822-7515, Fax (530) 673-5368, [email protected]
Luis Espino, CE Rice Advisor, UCCE Colusa,
100 Sunrise Boulevard, Suite E, Colusa, CA 95932
Phone (530) 458-0570, Fax (530) 458-4625, [email protected]
Timothy Blank, Certified Seed Program Representative, California Crop Improvement
Association,
1 Shields Avenue, Davis, CA 95616
Phone (530) 752-0544, Fax (530) 752-4735, [email protected]
Teresa De Leon, Plant Breeder, California Cooperative Rice Research Foundation,
Rice Experiment Station, 955 Butte City Highway, Biggs, CA 95917
Phone (530) 868-5481, Fax (530) 868-1730, [email protected]
Introduction
Rice (Oryza sativa L.) is an important crop in California (CA), grown on about 500,000
ha in nine counties in the Sacramento Valley (Hill et al., 2006). Weed control is the single largest
expense for growers on a per acre basis (Espino et al., 2016) primarily due to the high cost of
herbicides. Growers have few options for weed control other than herbicides, due to the unique
production system of continuously flooding to a depth of 10 cm, from seeding until
approximately one month before harvest. Flooding makes it impossible to use mechanical weed
management. In 2016, a particularly difficult to manage weed of rice, weedy rice (Oryza sativa f.
spontanea Rosh.) also known as weedy red rice, was found on widespread acreage,
approximately 4000 ha across eight counties. Weedy rice is considered to be one of the worst
weeds of rice worldwide (Wedger and Olson, 2018). In greenhouse studies in CA, weedy rice
potentially reduces yields by more than 70% percent at high densities (Brim-DeForest,
unpublished data). It is the same species as cultivated rice (Langevin et al., 1990), so it cannot be
managed using herbicides, as any herbicide used to control weedy rice would also destroy the
rice crop. Thus, for rice growers in CA, who rely heavily on herbicides, managing weedy rice
presents a particularly difficult problem. Furthermore, since it is the same species as cultivated
rice, identifying it in the field is extremely difficult.
Background in California
Weedy rice was first found in CA in the early days of commercial rice production
(Bellue, 1932). However, with the establishment of the certified seed program in the 1950’s, it
was widely thought to have been eradicated. In the early 2000’s, one biotype of weedy rice was
identified in six locations in two counties (Kanapeckas et al., 2016). A follow-up survey was
conducted in 2008, and no new infestations were identified. The California Crop Improvement
Association (CCIA), the certifying agency for the certified seed production in CA, found several
“off-types” in 2015, and concern increased later that year. By the spring of 2016, University of
California Cooperative Extension Rice Advisors and Specialists had begun alerting growers and
107
Pest Control Advisers to the potential weedy rice infestations. Reports came in throughout the
2016, and by the end of the season, a total of five distinct biotypes had been identified on over
4000 ha in eight counties. Over the next two seasons, growers and PCA’s continued to report,
and the acreage as of the end of the 2018 season increased only slightly. Another biotype was
found in 2018, for a total of six phenotypically distinct biotypes.
Domestication: How to Define a Weed
Since weedy rice and rice are the same species, one of the questions that has repeatedly
arisen, is why one rice plant is considered a weed, and one is considered a cultivar, when both
are edible and both are phenotypically (outwardly) similar? One of the characteristic phenotypic
differences is that many weedy rice biotypes have red pericarp, instead of the typical brown
pericarp, hence the anecdotal name weedy “red” rice. Using red pericarp alone, however, is
difficult in CA, where many cultivars also have red pericarp. So, the real question in CA became:
why is one red pericarped seed weedy and one not?
A distinguishing characteristic of a domesticated grain is its ability to retain its seeds until
maturity (Harlan, 1975; Hancock, 2004). Weedy or wild-type plants shatter (lose their seeds) at
or before maturity. Another domestication characteristic is the loss of seed dormancy (Harlan,
1975; Hancock, 2004). Many weedy or wild-type plants have primary or induced dormancy.
Thus, in general, to define a rice plant as “weedy”, it must have lost one or both of these
domestication traits: it is dormant, shattering, or both dormant and shattering. Other phenotypic
differences (pericarp color, hull color, awn length, etc.), are varied.
In CA, beginning in 2016, an aggressive research and extension program began. The
initial research that was deemed most essential was: 1) to identify and distinguish CA weedy rice
phenotypically from other weedy and cultivated rice; and 2) to determine CA weedy rice
biotypes’ genetic relationship to other weedy and cultivated rice. Identification is essential for
developing control strategies, especially if there are differences between biotypes, and the
genetic analysis was determined to be important in order to know how weedy rice was
introduced into CA and how it was moving within CA.
Phenotyping: Results
In 2016, weedy rice accessions from CA were collected and compared to CA cultivated
varieties, in particular the most widely-grown Calrose medium-grain varieties. The weedy rice
biotypes in CA have certain distinct characteristics, which can be used to distinguish them
phenotypically from cultivars in the field. On average, weedy rice phenotypes in California are
taller in height than the medium-grain Calrose cultivars, with less chlorophyll in their leaves (De
Leon et al., 2018). Using seed color and presence or absence of awns, the accessions were
classified into five distinct biotypes for the purpose of phenotyping in the field (De Leon et al.,
2018). The biotype found in 2018 (Type 6) has yet to be fully characterized. Seed dormancy and
shattering were also evaluated, but were not used to distinguish between the biotypes (Table 1).
108
Table 1. Generalized phenotypes for field characterization of the five weedy rice biotypes
identified in 2016, as compared to Calrose medium-grain cultivar, M-206. Biotypes were
characterized by dormancy (low or high), shattering (low or high), pericarp color (red or
brown), hull color (straw, gold, or black), awns (presence/absence), and grain type (short,
medium, or long).
Seed
Dormancy Shattering
Pericarp Color
Hull Color
Awns Grain Type
Weedy Rice Biotype 1
High High Red Straw Absent Short
Weedy Rice Biotype 2
Low High Red Gold Absent Long
Weedy Rice Biotype 3
High High Red Straw Present Medium
Weedy Rice Biotype 4
High High Red Black Present Medium
Weedy Rice Biotype 5
Low High Red Straw Absent Medium/Long
Calrose Cultivar M-206
Low Low Brown Straw Absent Medium
Genetics: Results
The methodology used for the genetic characterization of CA weedy rice can be found in
De Leon et al. (In Press). 46 CA weedy rice accessions were compared to 20 weedy rice
accessions from the Southern United States (US), and 8 wild rice accessions. They were also
compared to 22 cultivated japonica, indica and aus varieties from the US and Asia, including 2
specialty red-pericarped rice cultivars from CA. The CA weedy rice was determined to be from
multiple sources. Type 1 was most closely related to blackhull weedy rice from the Southern
United States, and aus cultivars (from Asia). Type 2 was most closely related to strawhull weedy
rice from the Southern US. For Types 3 and 4, one likely diverged from the other. Both were
most closely related to wild rice. Type 5 was most closely related to japonica cultivars (both
temperate and tropical), indicating possible hybridization in the field between weedy rice and
cultivated rice. The specialty (red-pericarped) cultivars grouped with Types 2 and 5, again
indicating possibel hybridization in the field.
Conclusion
Weedy rice is a unique and difficult to manage pest, since it is the same species as
cultivated rice. For effective weed control, it is imperative to be able to identify the pest in the
field. For weedy rice, this is complicated, especially since new phenotypes s are likely to emerge
over time, both through introductions and hybridization in the field. In-field surveys will need to
continue into the future, and another genetic analysis will need to be conducted, especially if new
phenotypes are found.
Literature Cited
Bellue, M. K. (1932). Weeds of California seed rice. California Department of Agriculture
Bulletin. 21, 290-296.
109
De Leon, T.B., Karn, E., Al-Khatib, K., Espino, L., Blank, T., Andaya, C.B., Andaya, V.C.,
Brim-DeForest, W.B. (2018). Genetic variation and possible origins of California weedy
rice: Origins of California weedy rice. Ecology and Evolution (In Press).
De Leon, T.B., Al-Khatib, K., Blank, T., Espino, L., Mutters, R., Leinfelder-Miles, M., Bruce
Linquist, B., Brim-DeForest, W.B. (2018). Weedy or not? Phenotypic characterization of
CA weedy red rice. In: Proceedings of the 2018 Rice Technical Working Group.
Espino, L.A., Mutters, R.G., Buttner, P., Klonsky, K. Stewart, D., Tumber, K.P. (2016). Sample
Costs to Produce Rice, Sacramento Valley. University of California Cooperative
Extension: 2016.
Hancock J.F. (2004). Plant Evolution and the Origin of Crop Species, 2nd edn. Cambridge, MA,
USA: CABI Publishing.
Harlan, J.R. (1975). Crops and Man. Madison, WI, USA: American Society of Agronomy.
Hill J.E., Williams J.F., Mutters R.G., Greer C.A. (2006). The California rice cropping system:
Agronomic and natural resource issues for long-term sustainability. Paddy Water
Environ. 4:13-9.
Kanapeckas, K. L., Vigueira, C. C., Ortiz, A., Gettler, K. A., Burgos, N. R., & Fischer, A. J.
(2016). Escape to ferality: the endoferal origin of weedy rice from crop rice through de-
domestication. PloS ONE, 11(9), e0162676.
Langevin, S.A., Clay, K., Grace, J.B. (1990). The incidence and effects of hybridization between
cultivated rice and its related weed red rice (Oryza sativa L.). Evolution, 44, 1000–1008.
Wedger, M.J., Olsen K.M. (2018). Evolving insights on weedy rice. Ecological Genetics and
Genomics, 7-8, 23-26
110
The Biology and Ecology of Field Bindweed (Convolvulus arvensis)
Lynn M. Sosnoskie, Agronomy and Weed Science Advisor, Merced and Madera Counties,
2145 Wardrobe Avenue, Merced, CA 95341
Phone (209) 385-7403, FAX (209) 722-8856, [email protected]
Bradley D. Hanson, Cooperative Extension Weed Science Specialist, UC Davis,
276 Robbins Hall, UC Davis, Davis, CA 95616
Phone (530) 752-8115, [email protected]
Background
Field bindweed (also known as corn-bind, perennial morningglory, possession vine, and
creeping jenny), is a deep-rooted and long-lived perennial vine in the Convolvulaceae family,
which is also the family of dodder (Cuscuta spp.), morningglories (Ipomoea spp.), and
alkaliweed (Cressa truxillensis). Its Latin name (Convolvulus arvensis), given to it by Carl
Linnaeus in his Species Plantarum (1753), roughly translates as ‘to entwine the field’, suggesting
that the species has been an agricultural pest for centuries. Bindweed is a native of the
Mediterranean region of Europe and of Western Asia and is believed to have been brought to the
United States in 1739 as a seed contaminant (Zouhar 2004). The species moved westward and
was officially documented in the state of California (San Diego County) in 1850 (CCH 2018).
By the first quarter of the twentieth century, Hilgard (1891) and Bioletti (1911) had proclaimed
the species to be the most troublesome weed in the state. According to the USDA PLANTS
database, field bindweed can be found throughout the United States and Canada where it is often
classified as common to abundant in cultivated fields and gardens, orchards and vineyards,
rights-of-ways, and other ‘disturbed’ sites (Zouhar 2004; USDA PLANTS 2018).
Bindweed Biology and Ecology
Field bindweed is a perennial vine that produces a deep and extensive root system;
vertical roots have been reported to reach depths of up to 30 feet. Lateral roots develop
adventiously from the taproot and are primarily contained in the top foot of soil. Rhizomes
develop from root buds and those that reach the surface form new crowns from which vines
develop (Weaver and Riley 1982; Whitson et al. 2000; Zouhar 2004) (Figure 1). Field bindweed
stems are twining and can form tangled mats. Leaf shape can be variable, although most are
triangular- to arrow-shaped (Figure 2).
Flowers are funnel shaped and white to pink in color (Figure 2). Flower peduncles arise
from leaf axils; field bindweed flowers are also subtended by a pair of short bracts (this is a
diagnostic tool for discriminating field bindweed from similar looking members of the
Convolvulaceae). Flowering begins in April and continues through September (or later) in
California (depending on latitude). Flowers open during the day and close tightly at night into a
twisted tube. Seeds are approximately 1/8th of an inch long, black in coloration, shaped like an
orange wedge, and produced in a papery capsule. Although estimates vary dramatically, it has
been reported that bindweed infestations can produce between 20,000 and 20,000,000 seeds per
acre (Brown and Porter 1942; Stripleng and Smith 1960; Swan 1980; Weaver and Riley 1982;
Whitson et al. 2000; Zouhar 2004).
111
Figure 1. Exhumed field bindweed roots and rhizomes. Vertical roots have been reported to
reach depths of up to 30 feet below the soil surface although lateral roots and rhizomes are found
primarily in the top 12 inches. Photo by L. M. Sosnoskie
112
Figure 2. Field bindweed flowers and leaves. Image from: USDA-NRCS PLANTS Database /
Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and
the British Possessions. 3 vols. Charles Scribner's Sons, New York. Vol. 3: 47.
The germinability of freshly produced bindweed seed is highest 20-30 days after
pollination; changes in seed moisture content and the permeability of the seed coat with time
result in a dormancy that requires future scarification to overcome. This hard-seededness is one
reason bindweed is so enduring in fields. Although viability does diminish with time, field
bindweed seed has been shown to persist in the soil for 20 to 30 years. Field bindweed
germination and emergence are impacted by burial depth: results from multiple studies have
suggested that most new plants emerge from depths of 2 inches or less. (Asgharipour 2011;
Benvenuti et al. 2001. Brown and Porter 1942; Stripleng and Smith 1960; Swan 1980; Weaver
and Riley 1982; Whitson et al. 2000; Zouhar 2004).
Field bindweed plants begin to develop their extensive system within 4 to 6 weeks of
emergence. This includes the production of latent buds that generate rhizomes from which new
crowns arise. New bindweed plants can also develop following the fragmentation of the root
system of a parent vine. According to published reports, the most regenerative tissues appear to
arise from root and rhizome pieces derived from the top 12 inches of soil. Fragment size can also
influence reestablishment success; root portions longer than 1 inch in length will enhance
regrowth potential (Sosnoskie, personal observation; Omezine and Harzallah-Skhiri 2010; Swan
and Chancellor 1976; Weaver and Riley 1982; Whitson et al. 2000; Zouhar 2004).
Implications for management
The biology of field bindweed can directly impact how easily it is controlled by physical,
chemical, and cultural control measures. The extensive root system and regenerative potential of
field bindweed necessitate frequent/continuous cultivation events to exhaust belowground
nutrient reserves. Results from Kansas trials conducted in the mid-20th century suggest that soil
disturbance to a depth of 3 to 5 inches every 2 to 3 weeks for 2 years is required to eradicate the
perennial vines (Timmins and Bruns 1951). Fallow cultivation to greater depths (8 and 12
inches) did not dramatically reduce the time required to eliminate field bindweed (Timmins and
Bruns 1951). Recommendations from the University of Idaho suggest conducting operations
under dry soil conditions because root fragments are less likely to grow when water is limiting
(Morishita et al. 2005). Tillage conducted under dry conditions will help to separate root
fragments from soil particles and facilitate desiccation (Morishita et al. 2005). It is important to
note that infrequent cultivation can actually facilitate the spread of field bindweed within a field
because rhizomes can regrow and photosynthesize and rebuild root nutrient reserves before the
onset of a following disturbance. Cultivation and tillage equipment can aid in the spread of
rhizomes both within and between fields, so it is critical to clean equipment after working on
infested acres. Mowing is usually not successful at controlling field bindweed as the plants
typically grow close to the ground. Hand-weeding is of limited efficacy because only
aboveground tissue is removed, and the remaining, intact roots will support regrowth.
The efficacy of foliar applications of glyphosate are also impacted by the species' roots;
or, more importantly, the movement of photosynthates from above ground tissue to storage
organs. The results of a study by Wiese and Lavake (1986) indicated that bindweed was more
susceptible to glyphosate during the late spring/early summer months (when plants were
113
flowering) as compared to early spring and late summer/early fall. There are multiple reasons for
the differences observed in sensitivity, one of which is that the phloem mobile glyphosate was
more readily translocated to meristematic tissues (including those in the root) where the
herbicide inhibits the synthesis of aromatic amino acids. The timing of glyphosate applications
can, therefore, dramatically affect herbicide performance. Systemic auxinic herbicides (i.e. 2,4-D
and dicamba) have shown activity against field bindweed, although the efficacy of the products
can be significantly reduced under drought conditions that result in stressed plants (Westra et al.
1992). Contact herbicides (i.e. paraquat and carfentrazone) burn back aboveground tissue, only;
although young seedlings may be controlled with the use of these products, the extensive root
system of field bindweed will support new shoot development. Multiple herbicide applications
are often required to suppress field bindweed, even if systemic herbicides are employed. Soil-
applied, residual herbicides have little activity of field bindweed, except for controlling emerging
seedlings. One exception is trifluralin, which can suppress perennial plants between 4 to 6 weeks
after treatment (Sosnoskie and Hanson 2016). Similar results were observed for another
perennial weed, Johnsongrass (Sorghum halepense), by Standifer and Thomas (1965).
With respect to cultural control methods, soil solarization may be effective at suppressing
bindweed top growth and reducing numbers of emerged seedlings, although deeply buried roots
are unlikely to be affected (Morishita et al. 2005). Field bindweed is not tolerant of shade and the
use of densely planted competitive crops has been suggested as a management tool. However,
shade can induce bindweed’s twining response encouraging the weed to climb up through the
crop canopy (Weaver and Riley 1982). Several insect pests (Tyta luctuosa, or European moth;
Chelymorpha cassidea, a tortoise beetle; and Aceria malherbae, a gall-forming mite) are known
to cause damage to field bindweed and have been evaluated for use as biological control agents.
Success has been limited to date; the use of biocontrol agents applied in conjunction with other
strategies may be required to achieve acceptable weed control (Morishita et al. 2005).
Summary
Field bindweed is an increasing concern of growers in the Central Valley of California,
especially those that are producing crops in reduced tillage/drip-irrigated systems. With a limited
number of effective herbicides available (i.e. trifluralin in processing tomatoes, glyphosate in
glyphosate-resistant agronomic commodities), the problem is not likely to be eliminated in the
short-term. Additionally, most of the published field bindweed research has been conducted in
environments that differ, substantially, from California’s Mediterranean climate. The
development of field bindweed, and its subsequent response to chemical, physical, and cultural
control measures, in environments that experience greater amounts of rainfall, higher relative
humidity, and freezing winter conditions may not be adequately represent the types of results
that will be achieved in much of the Western US. While it is not necessary to recreate the wheel
with respect to bindweed research, it is probably advisable to understand that bindweed adapted
to the hotter and drier conditions in California may be more tolerant of some recommended
control practices. Lastly, the impact of climate change on perennial weed behavior cannot be
ignored. How will increasing temperatures and variable precipitation affect bindweed growth,
development, and dormancy? Will the vegetative growing season for field bindweed expand and
how will this affect the availability and performance of management tools? It is important to
study how bindweed responds to control tools, now; it is equally important to be proactive about
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future environments that can dramatically impact our ability to suppress an already difficult-to-
control species.
References
Asgharipor, M. R. 2011. Effects of Planting Depth on Germination and the Emergence of Field
Bindweed (Convolvulus arvensis L.). Asian J. Ag. Sci. 3:459-461.
Benvenuti, S. et al. 2001. Quantitative analysis of emergence of seedlings from buried weed
seeds with increasing soil depth. Weed Sci. 49:528-535.
Bioletti, F.T. 1911. The extermination of morning glory. Calif. Agric. Exp. Stn. Circ. 69.
Brown, E. O. and Porter, R. H. 1942. The viability and germination of seeds of Convolvulus
Arvensis L. and other perennial weeds. Res. Bull. - Iowa Ag. Home Econ. Expt. Stn. 25:294.
[CCH] Consortium of California Herbaria (2018). Field Bindweed Specimen Records.
http://ucjeps.berkeley.edu/cgi-bin/get_consort.pl?taxon_name=Convolvulus%20arvensis
Accessed on: 14 December 2018.
Hilgard, E.W. 1891. The weeds of California. Calif. Agric. Exp. Stn. Rep. 1890:238-252.
Morishita, D. et al. 2005. Field bindweed. Convolvulus arvensis L.:Convolvulaceae.
http://www.cals.uidaho.edu/edComm/pdf/PNW/PNW0580.pdf Accessed on: 14 Decenber 2018.
Omezine, A. and F. Harzallah-Skhiri. 2010. Field Bindweed biology and growth resumption.
Afric. J. Plant Sci. Biotech. 4:33-38.
Sosnoskie, L. M. and B. D. Hanson. 2016. Field bindweed (Convolvulus arvensis) control in
early and late-planted processing tomatoes. Weed Technol. 30:708-716.
Standifer, L. C. and C. H. Thomas. 1965. Response of Johnsongrass to soil incorporated
trifluralin. Weeds 13:302–306.
Stripleng A. and F. H. Smith. 1960. Anatomy of the seed of Convolvulus arvensis. Am. J. Bot.
47: 386–392.
Swan, D. G. 1980. Field bindweed, Convolvulus arvensis L. Wash. State Univ. Coll. Ag. Res.
Bull. 0888.
Swan, D. G. and R. J. Chancellor. 1976. Regenerative capacity of field bindweed roots. Weed
Sci. 24:306–308.
Timmons, F. and V. Bruns. 1951. Frequency and depth of shoot cutting in eradication of certain
creeping perennial weeds. Agron. J. 41:130-133.
115
[USDA PLANTS] United States Department of Agriculture PLANTS database. 2018. Field
Bindweed Records. https://plants.usda.gov/core/profile?symbol=COAR4 Accessed on: 14
December 2018.
Weaver, S. E. and W. R. Riley. 1982. The biology of Canadian weeds. 53. Convolvulus arvensis
L. Can. J. Plant Sci. 62: 461-472.
Westra, P. et al. 1992. Field bindweed (Convolvulus arvensis) control with various herbicide
combinations. Weed Technol 6:949–955.
Whitson, T. D. et al. 2000.Weeds of the West. Laramie, WY. 630 pp.
Wiese, A. F. and D. E. Lavake. 1986. Control of field bindweed (Convolvulus arvensis) with
postemergence herbicides. Weed Sci 34:77–80.
Zouhar, K. 2004. Convolvulus arvensis. In: Fire Effects Information System (FEIS).
116
2019
Session #8
Nutrient Management
Session Chairs:
Daniel Geisseler
Mark Cady
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Potassium and Phosphorus Management in Orchards
Franz Niederholzer
Farm Advisor
University of California Cooperative Extension Colusa, Sutter & Yuba Counties
Cooperative Extension Colusa County
PO Box 180, 100 Sunrise Boulevard, Suite E
Colusa, CA 95932
(530) 458-0570
http://cecolusa.ucanr.edu
http://www.twitter.com@Hwy20orchardoc
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Comparing Nitrogen Management Practices for Pima and Acala Cotton
Under San Joaquin Valley Growing Conditions
Bob Hutmacher, University of CA Cooperative Extension Specialist
UC West Side REC and UC Davis Plant Sciences Department,
PO Box 158, Five Points, CA 93624
Phone (559) 884-2411. Ext 206; FAX (559) 884-2216; [email protected]
Introduction
Over the past three decades, California cotton production has shifted from nearly all
acreage being planted to specialized Upland cotton varieties (the sub-group of high-quality
Uplands called “Acala” cotton) to Pima cotton, with recent years reaching over 85% of total
acreage in Pima (USDA-Economic Research Services). As a premium-quality cotton, Pima
commands a significantly higher price than Acala / Upland cotton, so if high enough yields can
be consistently achieved, Pima will likely remain the dominant planted cotton in California in
future years. However, Pima varieties on the average require a 2-3 week longer growing season
than most Uplands, and there are known differences in sensitivity to insect pests, impacts of
plant water stress on fruiting, and plant responses to management practices such as use of plant
growth regulators (Hutmacher et al, 2004; Silvertooth and Norton, 2011; Unruh and Silvertooth,
1996 in Arizona and some unpublished CA studies (Hutmacher, unpublished)) have
demonstrated that petiole nitrate guideline recommendations for Pima differ greatly from those
developed for Uplands. As with Upland cotton, good nitrogen (N) management decisions in
Pima are known to impact various aspects of crop management and input costs, including
vegetative:reproductive growth balance, insect pest pressure, timing of maturity, and ease of
defoliation. Since cotton produces a high protein content seed, many prior studies in Upland
cotton have shown that close to harvest timing, the bolls contain typically 50-60% or more of
total above-ground late-season plant N. The seed are the primary sink for N in the boll, with
very low concentrations of N in the boll structural tissue or in the lint. Under CA conditions
where we leave essentially all leaf and stem materials in the field at harvest, most N removal
with harvest should be in the seed.
With the exception of the Arizona studies mentioned above and a few small nitrogen
uptake measurements made as part of irrigation studies conducted by the project team
developing this proposal, we are not aware of arid or semi-arid zone research done specifically to
identify whether or not N management recommendations and guidelines developed for Upland
cotton are applicable to Pima cultivars. Most past research related to nitrogen management in
cotton has focused on Upland cotton varieties, which continue to be the primary type of cotton
produced in other parts of the U.S. (Bronson et al, 2017; Bronson et al, 2017; Hutmacher et al,
2004; Bassett and MacKenzie, 1983). With the exception of petiole nitrate guidelines, most
growers base N management decisions on their own Pima experiences in combination with
available recommendations based on Upland cotton research. More Pima-specific information
would assist in efforts to fine-tune nitrogen management practices, avoid negatives associated
with inadequate or excess N applications, and provide improved N removal estimates to be used
in nitrogen management plans for CA producers. Additional details of Pima-specific nitrogen
management recommendations would also be of assistance in trying to deal with improved
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nitrogen management practices dictated in response to groundwater nitrate contamination
concerns associated with irrigated crop production (Harter et al, 2012).
Petiole Nitrate Guidelines – Differences Between Pima and Uplands
Studies conducted in Arizona and California during the past decade or more have
consistently shown differences in prevailing petiole nitrate levels of upper canopy leaves in
terms of sufficient, borderline and deficiency levels at different growth stages (Silvertooth and
Norton, 2011; Hutmacher et al, 2004; Hutmacher, unpublished). Table 1 shows values derived
from University of California cotton irrigation and nitrogen management studies, with all of
these studies conducted in furrow irrigated and drip irrigated cotton grown in a clay loam soil at
the University of CA West Side REC near Five Points in western Fresno County. All this data
was based on measurements made on multiple Upland cultivars (Daytona RF, Phy 72, Phy 725
RF) and multiple Pima cultivars (Phy 802 RF, Phy 805 RF, and DP 348 RF).
Table 1. Petiole nitrate guidelines for Upland and Pima types of cotton as a function of growth
stage. Guidelines show a range of values representative of plants considered to be “Borderline to
Deficient” or “Upper Level of Sufficient Range”. Data collected on furrow- irrigated and drip
irrigated cotton over a 7 year period in a clay loam soil at the Univ. CA West Side Research and
Extension Center, Five Points, CA. Growth Stage Upland Cotton Pima Cotton Borderline to
Deficient Sufficient – Upper Level of sufficient
Borderline to Deficient
Sufficient – Upper level of sufficient
Early squaring <14,000 >20,000 <10,000 >12,000-14,000 First flower <11,000-12,000* >14,000-18,000 <6,000-7,000 >9,000-10,000 First flower + 10 days
<8,000-10,000 >12,000-14,000 <4,000-5,000 >6,500-8,000
Peak bloom <3,500-5,500 >7,000-9,000 <2,500-3,500 >4,500-6,000 Early open boll <1,500-2,000 >3,500-4,500 <1,000-1,500 >2,500-3,000 10-15 days after vegetative cutout
<750-1,200 >1,500-2,000 <750-1,000 >1,250-1,500
* In this table, when there is a range of values shown for borderline/deficient or sufficient levels,
the lower end of the range has been found to more typically represent subsurface drip irrigated
cotton where N fertigation is used to spread out N fertilizer applications over a multi-week or
multi-month period, while the upper end of the range has been found more often to better
represent furrow irrigated cotton in a deep soil with good rooting depth, especially when N
fertilizer has been applied in approximately a 50/50 split with half applied just prior to or at
planting, and the remaining half applied just prior to first within-season furrow irrigation (about
2-3 weeks prior to first flower).
Plant N Uptake and Harvest Removal Estimates and Issues – Pima versus Uplands
As part of our University of CA Cooperative Extension field research efforts in several
irrigation projects, we have been collecting some limited information as a side project on above-
ground plant nutrient uptake measurements in both Upland and Pima types of cotton. All of this
work has been done over a number of years at the University of CA West Side Research and
Extension Center (WSREC). The nitrogen component of these studies was only a subset of the
work on the overall projects, so much of this work was done with limited replications and only at
one site, and has not been published to date. A primary reason to mention these limited field
120
studies, however, is to point out that we have some data on N uptake and removal for both Pima
and Upland / Acala types of cotton, and some values in those data sets differ from values shown
in the cotton section posted for cotton on the California Department of Food and Agriculture
FREP (Fertilizer Research and Education) website, particularly the one data set mentioned for
Pima types of cotton (CDFA, Fertilizer Research and Education Program). Values for cotton
shown on that website show an average N removal with harvest of 43.7 lbs N per ton of lint and
plus seed harvested in studies that include one Pima site and data set, plus data from Upland
varieties from data collected in California, Israel, Greece and Syria. The values shown in those
limited studies (7 observations total) for Pima types of cotton (Fritschi, et al, 2004) indicated an
average value of N removal of 33.1 lbs N/ton of lint plus seed, suggesting that removal in Pima
is much lower than the average value of 43.7 lbs N/ton of lint plus seed, an average which mostly
represents Acala and non-Acala Upland types of cotton. The Pima studies referred to, which
were also conducted at the West Side REC, were relatively limited in number, and represented
lower yield situations than those now achieved by commercial Pima growers in California.
The limited uptake data from small plot irrigation studies (unpublished to date) conducted at the
UC West Side REC over the past 9 years is shown in the table below, noting the averages and
relatively large standard deviations for:
(a) harvest-time total plant N uptake (lbs N in above ground plant parts/acre) and
(b) N removal in lint plus seed with harvest (in lbs N/ton of lint plus seed)
The values shown in table 2 were determined using small area harvests in field research plots in
a clay loam soil, under furrow irrigation at the UC West Side REC, with plants partitioned into
different components, weighed, and then subsampled to determine N content.
Table 2. Total above-ground plant nitrogen (N) uptake at defoliation timing, and mean, standard
deviation and range of values determined for N removal with harvest in lbs per ton of seedcotton
(lint plus seed) in studies conducted at the University of CA West Side Research and Extension
Center from 2006 through 2015.
Type of cotton Total Plant N Uptake in these studies (above-ground) Mean and std deviation
Total Plant N Uptake in these studies (above-ground) Range of values
N Removal with harvest (in lint plus seed) (lbs N/ton of lint plus seed) Mean and std deviation
N Removal with harvest (in lint plus seed) (lbs N/ton of lint plus seed) Range of values
Total number of
observations used for averages
shown
Pima cotton 216.4 +/- 28.9 161 to 265 43.9 +/- 3.1 36 to 48 14*
Acala types of Upland cotton
204.5 +/- 31.3 163 to 258 41.9 +/- 2.3 38 to 44 8*
Non-Acala Upland types
205.8 +/- 29.8 172 to 239 41.5 +/- 3.2 38 to 45 5*
* generally there were three samples replicates per site for these evaluations.
As can be observed in the table of information provided above, the average values that we have
for N removal with harvest for Pima types of cotton are actually quite similar to those in some
121
more limited studies we have done using Acala and Upland varieties, as compared to the lower
values shown for Pima by Fritschi et al (2003, 2004), which were based on two studies done with
one Pima cultivar at this same test site (West Side REC), but with significantly lower seedcotton
yields. In order to more precisely evaluate Pima cotton N uptake and removal, new studies will
be undertaken starting in 2019 to determine if cultivars differ based on seed size or yield
potential at different sites, and at the West Side REC we will compare uptake and removal
differences under furrow versus subsurface drip irrigation.
Literature Cited
Bassett, D.M., and A.J. MacKenzie. 1983. Plant analysis as a guide to cotton fertilization. In:
H.M. Reisenauer (ed.), Soil and Plant Tissue Testing in California, pp. 16 Berkeley, Univ.
CA, Div. Agric. Sci., Bulletin 1879.
Bronson, K., D.J.Hunsaker, J. Mon, P. Andrade-Sanchez, J.W. White, M.M. Conley, K.R.
Thorp, E. Bautista, E. M. Barnes. 2018. Improving Nitrogen Fertilizer Use Efficiency in
Surface and Overhead Sprinkler-Irrigated Cotton In the Desert Southwest. Soil Sci. Soc.
Am. J. 81:1401-1412.
CDFA, Fertilizer Research and Education Program – Nutrient Management Guidelines.
https://apps1.cdfa.ca.gov/fertilizerresearch/docs/guidelines.html
Fritschi, F.B., Roberts, B.A., Travis, R.L., Rains, D.W., Hutmacher, R.B., 2003. Response of
irrigated Acala and Pima cotton to nitrogen fertilization: growth, dry matter partitioning, and
yield. Agronomy Journal 95, 133-146.
Fritschi, F.B., Roberts, B.A., Travis, R.L., Rains, D.W., Hutmacher, R.B., 2004. Seasonal
nitrogen concentration, uptake, and partitioning pattern of irrigated Acala and Pima cotton as
influenced by nitrogen fertility level. Crop Science 44, 516-527.
Harter, T., J.R. Lund, J. Darby, G.E. Fogg, R. Howitt, KK. Jessoe, G. Stuart Pettygrove, J.F.
Quinn, J.H. Viers. 2012. Addressing Nitrate in California’s Drinking Water. With a Focus
on Tulare Lake Basin and Salinas Valley Groundwater. Report for State Water Resources
Control Board – Groundwater
Hutmacher, R. B., L. Travis, W. Rains, B. A. Roberts, M. Keeley, B. Weir, R. Vargas, D. Munk,
B. Marsh, S.D. Wright, and R. Delgado. 2000. Growth Stage Impacts on Nitrogen
Distribution, Uptake of Acala Cotton. Beltwide Cotton Production Conference Proceedings,
San Antonio, TX. Natl. Cotton Council, Memphis, TN.
Hutmacher, R.B., R.L. Travis, D.W. Rains, R.N. Vargas, B.A. Roberts, B.L. Weir, S.D. Wright,
D.S. Munk, B.H. Marsh, M.P. Keeley, F.B. Fritschi, D.J. Munier, B.L. Nichols, R. Delgado.
2004. Response of Recent Acala Cotton Varieties in Variable Nitrogen Rates in the San
Joaquin Valley of California. Agron. J. 96:48-62.
Navarro, J.C. et al. 1997. Fertilizer nitrogen recovery in irrigated Upland Cotton. Cotton
College of Agric. Report, Series P-108, Univ. AZ, Tucson, AZ, p. 402-407.
Silvertooth, J.C., E.R. Norton. 2011. Univ. AZ Coop Ext. Bulletin AZ-1243.
Unruh, B.L. and J.C. Silvertooth. 1996. Comparisons between an upland and a pima cotton
cultivar: II. Nutrient uptake and partitioning. Agron. J. 88:589-595
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Nutrient Management of Forage Crops
Nicholas Clark, UCCE Farm Advisor in Kings, Tulare, & Fresno Counties
680 N. Campus Dr., Ste. A, Hanford, CA 93230
Phone (559) 852-2788, FAX (559) 582-5166, [email protected]
Introduction
Forage crops for the dairy industry in the southern San Joaquin Valley (SJV) account for
approximately 765,000 planted acres each year. Slightly less than 215,000 acres are in alfalfa
hay and chop, and the remainder is split pretty evenly between double crop corn and winter
cereals such as wheat, triticale, barley, oats, and rye. In dryer years, up to 90,000 acres of
summer forage might be planted to sorghum. Most of these acres are on ground that have long
histories of fertilization and amendment with dairy manure of various forms. Some of that
ground is regularly fertilized with synthetic fertilizers. Typically, these are fields that are not
easily fertilized with manure due to distance from the dairy facility, lack of infrastructure to
deliver manure, or simply not enough manure to meet total farm demand for crop nutrients.
Alfalfa fields are the exception in that they are seldom fertilized with manure and are almost
always fertilized with commercial fertilizers.
Nearly 13 million tons of forage (hay, silage, and green chop combined) are produced
annually from Fresno County south to the Tehachapi Mountains to support feeding about 2
million milk cows and their replacements. This paper will review some literature that describes
how to plan a fertilizer program for those forages with macronutrients to maintain sustainable
production as well as mitigate potentially harmful environmental impacts. In particular, some
challenging aspects of fertilizing forage crops with manure will be discussed.
Crop Nutrient Requirements
Field by field yield achievements should be utilized to set yield goals in order to estimate
annual crop nutrient requirements. Known values of crop nutrient removal can be used to
calculate how much of a total nutrient will be removed by a crop within the growing season.
Knowing and tracking these values is foundational for either replacing nutrients (such as
nitrogen) or maintaining soil nutrient concentrations at sufficient levels (such as phosphorus and
potassium).
For fertilizing forage with nitrogen, a grower should first utilize a budget approach to
determine how much nitrogen (N) should be applied within the season. That is, start with the
total amount of nitrogen a crop will use, then subtract credits to the system and account for losses
due to inefficiency. Macronutrient removal by corn, for example, is well known (Bender et al.,
2012; Ciampitti et al., 2013; Geisseler, 2016; Hart et al., 2009; Karlen et al., 1987; Karlen et al.,
1988; Pettygrove & Bay, 2009; Ludwick et al. (Eds.), 2002) (Table 1). Therefore, a field that is
expected to yield 30 tons/acre will remove about 222 lbs N/acre from the soil (30 tons corn/acre
* 7.4 lbs N/ton corn). A soil test shows there are 80 lbs N/acre of plant available residual soil N.
The farmer can discount that N from the N application requirement, diminishing it to 142 lbs
N/acre (222 lbs N/acre – 80 lbs N/acre). Still, due to the high reactivity of N forms in the soil N
cycle, N fertilizer recovery is relatively inefficient (70%). The farmer should then increase the
application requirement to adjust for the 30% loss of N (volatilization, denitrification,
immobilization, and leaching) to 202 lbs N/acre (142 lbs N/acre / 70%).
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Following the corn example, to fertilize with phosphorus (P) and potassium (K), preplant
soil test values are best at determining if a fertilizer application is necessary. Soils testing
between 6-12 ppm Olsen P in the top 12” of soil are within the sufficient range of P for corn
(Table 2). Replacing the annual P removed with harvest should keep the soil test within this
range. Fertilization with P when soil test values are over 12 ppm are unlikely to increase yield.
When soil test values are lower than 6 ppm, higher rates of P fertilizer are likely required, but
should be economically sustainable. A broadcast preplant plus a banded starter application of a P
fertilizer is a good way to ensure efficient recovery of P from the soil as the corn roots grow
throughout the season (CDFA FREP, 2018).
Table 2. Soil test sufficiency ranges for various forage crops. Crop Olsen P Extractable K (ammonium acetate) ppm ppm Corn1 6 – 12 50 – 80 Wheat1 6 – 12 40 – 60 Alfalfa2 10 – 20 80 – 125 1 CDFA FREP (2018) 2 Meyer et al. (2007)
Soil test K (ammonium acetate extraction) values between 50-80 ppm in the top 12” of
soil are within the sufficient range of K for corn. Replacing K removed with harvest will likely
maintain these soil test values. Fertilization with K when soil tests are above the sufficiency
range are unlikely to result in a yield increase, where K fertilization should be greater than
expected crop removal when soil test values are below the sufficiency range. Broadcasted
applications should be incorporated to increase uptake efficiency since K is usually immobile in
soil (excepting very sandy soils with low organic matter content). Banding increases uptake
efficiency. Starter K should be banded up to 2 inches below and 2 inches to the side of the seed
to reduce salt injury to young roots (Table 3). Success with increasing yields with starter K
fertilizer is variable (CDFA FREP, 2018).
Table 1. Macronutrient removal by crop harvest at standard moisture in literature Crop --------------------Lbs nutrient/ton harvested crop--------------------
Nitrogen Phosphorus Potassium
Corn 7.4 1.5 6.4 Wheat, boot1 11 1.7 8.3 Wheat, soft dough1 16 2.8 12 Alfalfa2 58 5.9 44.9 1 Pettygrove & Bay (2009) 2 Meyer et al. (2007); Ludwick et al. (Eds.) (2002)
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Table 3. Maximum amount of N plus K2O, based on distance from seed (adapted from Western Plant Health Association (2002) to 30 inch rows)
Placement Sandy Soils Fine-Textured Soils
(lbs/A) (lbs/A)
In contact with seed1 7 7-10
0.25 - 0.5 in. from seed 10 9-20
1 - 2 in. from seed 20 26-52
> 2 in. from seed2 26+ 52+ 1 Seed placement in dry or sandy soils is advised against by CDFA-FREP (2018) 2 Rates greater than 70-80 Lbs/A are advised against by CDFA-FREP (2018)
Meeting Crop Nutrient Demand in Time
Crops remove nutrients from the soil over their life cycle, and the rate of removal is not
constant. Knowing when the phases of least and greatest crop nutrient demand occur is important
in order to ensure nutrients are available to the crop at the most critical times to avoid limiting
yield or losing nutrients to the environment. Thus a fertilizer plan can be developed and executed
which aims to supply nutrients to the crop in the amount needed just as the crop demands.
Annual crops such as corn and wheat can be fertilized annually if needed with P and K
fertilizers, and generally preplant fertilization is sufficient to ensure crop demand and any
necessary soil P or K building are met. Fertilizing with N requires more attention to timing of
application due to the higher mobility of N in soil. Typically, only small amounts, if any N
should be applied preplant. Soils that supply at least 40 lbs per acre foot of residual nitrate can
probably sustain corn until a knee-high side dress of N or wheat until an early tiller topdress or
water-run N when biomass accumulation and N accumulation rates typically begin to accelerate.
Ciampitti et al. (2013) showed that 8 leaf corn (V-8) grown on N sufficient soil had taken up
approximately 60 lbs N/acre while Karlen et al. (1987) showed that corn at V-10 had taken up
approximately 45 lbs N/acre. Both showed that the corn at these stages was rapidly increasing N
uptake. These results are in agreement with recent research conducted in the south SJV (Clark et
al., unpublished) where at V-10 the corn had accumulated 50 lbs N/acre.
Fertilization of corn with N at a knee-high side dress should consider that the crop has
only taken up about 20% of its required seasonal N. By the time the crop reaches silking,
Ciampitti et al. (2013) and Karlen et al. (1987) demonstrated that the crop is approximately 70%
finished with N uptake and that the rate has slowed significantly. These observations were also
made in the south SJV. Thus, any fertilization at or past silking should be proportional in rate
and designed to be highly available to the crop.
Alfalfa can be fertilized preplant with up to three years’ worth of P fertilizer without
sacrificing efficiency, but economic feasibility might be a constraint. Thus, annual top-dress
applications of P fertilizer during dormancy is a common practice. Potassium fertilization can
also be made to supply several years of crop demand, but care should be taken to limit a single
application to less than 300 lbs K2O/acre to avoid salt injury to roots (Meyer et al., 2007).
Typically, K fertilization is not needed in CA except under high precipitation over sandy, low
OM% soils with a history of K deficiency. Nitrogen fertilizer is seldom needed in alfalfa since
the plants’ symbiotic relationship with Rhizobium meliloti provides the crop with all of the N it
needs for full growth by fixing it from the atmosphere.
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Utilizing Manure as a Fertilizer Source
Dairy manure is highly rich in plant nutrients, and it is stored on dairy facilities in
multiple forms. Nutrient concentrations and other chemical properties are highly dependent on
the form of manure stored but can also vary greatly within the course of a year on a given dairy
and especially between dairies. General nutrient concentrations are known for the various forms
of manure, but it is prudent (and often required by regulations) to sample manure for nutrient
concentration determination in order to practice good crop fertility management. Some manure
nutrient concentrations and properties are shown in Table 4 (adapted from Pettygrove et al.,
2010).
Table 4. Examples of nutrient concentrations and salinity of several manure forms. Total N NH4-N P K EC ppm 1 dS/m 1
Lagoon water
360 (36–2420)
257 (10–554)
72 (9–380)
497 (35–1040)
4.6 (0.7–9.6)
% dry wt 2 dS/m 3
Solids 4 2.1 (1.2–3.5)
0.13 (0.0013–0.63)
0.41 (0.18–1.99)
0.57 (0.15–4.37)
4.1 (1.7–36)
1 Average of median values from several dairies with range of values shown in parentheses 2 Median value with range shown in parentheses 3 Measured on saturated paste extract 4 Represented by corral scrapings, setting pond solids, screened solids, and composts
Another challenge with manures as fertilizers is that they do not come pre-formulated
with guaranteed analysis of nutrient concentrations. In other words the farmer has to take what
they get and thus consider the potential for over- or under-applying one or more nutrients for the
sake of targeting an ideal application of another nutrient. For example, fertilizing forage crops
with manure to meet the total N demand of those crops will generally over-fertilize with P and K.
This is because the N:P and N:K removal ratios of the forage crops are usually higher than the
N:P and N:K ratios of manure content. Table 5 presents an example of how this problem is
manifested. Due to the inherent inefficiency of N fertilizer, if the farmer were to increase the
application of lagoon water N to account for volatilization, for example, the ratio of P applied to
P removed would immediately rise above 1, creating a soil P building situation. It is very
common for dairy forage fields with history of regular manure applications to be very high in
soil test P and K. Generally, this is not a problem unless P runoff is a risk for adjoining public
surface water or if alfalfa hyper-accumulates K and the animals’ total mixed ration is not
corrected for high monovalent cation concentration which will contribute to milk fever. Farmers
should consider fertilizing with manure to meet the crop’s P or K demand rather than the N
demand. The remainder of crop N demand could be met with synthetic N fertilizers.
Table 5. Ratios of manure macro-nutrients content compared to corn macro-nutrient removal
N P2O5 K2O
Manure as solids 2.2 1 0.7
Lagoon water 2.2 1 3.6
Corn removal 2.3 1 2.3
126
One more significant challenge of fertilizing with manure is the high and varying fraction
of N in the organic form which is not immediately available to plants. Thus, timing of
application must consider the time required for organic N to be mineralized by soil microbes.
Very little to a majority of the organic N, largely depending on the source and C:N ratio, may be
mineralized within the first year after application, and it continues to mineralize for several
years. This challenge is of particular importance when considering dairies in CA are regulated on
how much total N can be applied to a given field relative to how much N is removed by the
crop’s harvest which is limited to 140%. It’s possible that a dairy farmer be penalized for “over-
applying” N without the benefit of that N every being available to their crop (remains in the
organic form, stable in the soil). Pettygrove et al. (2009) compiled information from several
studies to illustrate the variable rates at which manure N mineralizes by source and by time
(Table 6).
Table 6. Percent of organic N mineralized from various manures over time Year 1 Year 2 Lagoon water 40-50 15 Lagoon sludge; corral scrapings 20-30 15 Screen solids 10-20 5 Composted manure 0-10 5 Solid poultry manure 50 15
Literature Cited
Bender, R. R., Haegele, J. W., Ruffo, M. L., & Below, F. E. (2012). Nutrient Uptake,
Partitioning, and Remobilization in Modern, Transgenic Insect-Protected Maize Hybrids.
Soil Fertility & Crop Nutrition, 105(1), 161-170.
CDFA, FREP, & UCD. (2018) California Fertilization Guidelines. Retrieved from
https://apps1.cdfa.ca.gov/fertilizerresearch/docs/guidelines.html
Ciampitti, I. A., Camberato, J. J., Murrell, S. T., & Vyn, T. J. (2013). Maize Nutrient
Accumulation and Partitioning in Response to Plant Density and Nitrogen Rate: I.
Macronutrients. Crop Ecology & Physiology, 105(3), 783-795.
Geisseler, D. (2016). Nitrogen concentrations in harvested plant parts - A literature overview.
Hart, J., Sulluvan, D., Gamroth, M., Downing, T., & Peters, A. (2009) Silage Corn. Nutrient
Management Guide. Western Oregon: Oregon State University.
Karlen, D. L., Sadler, E. J., & Camp, C. R. (1987). Dry Matter, Nitrogen, Phosphorus, and
Potassium Accumulation Rates by Corn on Norfolk Loamy Sand. Agronomy Journal, 79,
649-656.
Karlen, D. L., Flannery, R. L., & Sadler, E. J. (1988). Aerial accumulation and partitioning of
nutrients by corn. Agronomy Journal, 80, 232-242.
Ludwick, A. E., Bonczkowski, L. C., Buttress, M. H., Hurst, C. J., Petrie, S. E., Phillips, I. L., . .
. Tindall, T. A. (Eds.). (2002). Western Fertilizer Handbook (9 ed.). Long Grove, Illinois:
Waveland Press Inc.
Meyer, R. D., Marcum, D. B., Orloff, S. B., & Schmierer, J. L. (2007). Alfalfa fertilization
strategies. In C. G. Summers & D. H. Putnam (Eds.), Irrigated alfalfa management for
Mediterranean and Desert zones. Oakland: Regents of the University of California.
Pettygrove, G. S., & Bay, I. (2009) Crop Nutrient Harvest Removal. Manure Technical Guide
Series. Oakland: Regents of the University of California.
127
Pettygrove, G. S., Heinrich, A. L., & Crohn, D. M. (2009) Manure Nitrogen Mineralization.
Manure Technical Guide Series. Oakland: Regents of the University of California.
Pettygrove, G. S., Heinrich, A. L., & Eagle, A. J. (2010) Dairy Manure Nutrient Content and
Forms. Manure Technical Guide Series. Oakland: Regents of the University of
California.
128
2019 Poster Abstracts
Poster Committee
Daniel Geisseler, Chair
129
1. Undergraduate Student
THE EFFECTS OF CULTIVATION PRACTICES OF ALMOND ON
SUBSEQUENT CROP IN ROTATION
Lucio Bahena, Alejandra Gonzalez, Chloe Dugger, and Hossein Zakeri
California State University, Chico
Contact: Hossein Zakeri, CSU Chico, 400 W. 1st St., Chico CA, 95929
530-898-5753; [email protected]
California is the world’s largest almond producer, producing about 80% of the world’s annual
almonds. Long-term almond management practices, such as weed and pest management, tree
management, harvesting, nutrient management, irrigation, etc., during the lifetime of almond can
have significant impacts on soil properties and subsequent crops in rotation. However, these
effects are less likely to appear when orchard is renewed after heavy cultivation and plow.
We have observed and studied the growth and yield of flax in a field that had been under almond
production for over 30 years. The trees were pulled from the ground and the field was prepared
during the fall of 2017 and flax was planted in November of 2017 and again in October of 2018.
In other years, we observed that flax germination and establishment was significantly different in
rows that previously had almond (tree-rows) compared to the rows that previously were alleys.
In the first year, flax germinated and produced vigorous seedlings in tree-rows, but had relatively
low germination rate and very poor seedling vigor in alley rows. After studying the field history,
we assumed the variations were associated with previously herbicide application in the almond
alleys. However, effects disappeared once plants reached the stem elongation stage, and plants
produced similar yield by harvesting. In 2018, we established a field trial in the same field to
compare several flax varieties in early October. Again, we observed the same effects on the flax
crop. We have established several bioassay trials and testing different hypothesis to determine
possible reasons for varied germination and seedling vigor on tree-rows and alleys. Specifically,
we are testing if the variations are associated with soil compaction, soil nitrogen content, soil
organic matter content, and allelopathic effects of almonds.
Flax was sown in two sets of trays that are filled with soil from the tree-rows and alleys. One set
of trays are in greenhouse and the other set are outside. Appropriate treatments were applied to
test the hypothesis. Seed germination rate and seedling establishment will be quantified and
presented in details.
130
2. Undergraduate Student
FUSARIUM FALCIFORME IS A PREVIOUSLY UNRECOGNIZED
PATHOGEN OF COWPEAS, PRESENT IN CALIFORNIA
Andrea C. Bourquin1, Nick Clark2, Cassandra Swett1
1University of California, Davis, 2University of California Cooperative Extension Kings, Tulare,
and Fresno Counties
Contact: Andrea C. Bourquin, UC Davis, Department of Plant Pathology, One Shields Ave.,
Davis, CA 95616
530-752-3831; [email protected]
Vigna unguiculata (common name: cowpea or black eyed pea), is an important member of dry
bean production for many countries, including the United States. In 2018, Fusarium falciforme
was consistently recovered from cowpeas suffering from crown and root rot from one site in
California. Although this species had not been documented as a pathogen of cowpea, it is known
to cause crown rot in lima beans in Brazil, leading us to hypothesize that it is also a pathogen of
cowpea. To test this hypothesis we conducted Koch’s postulates, evaluating four F. falciforme
isolates from cowpea and one from tomato (which is also a host); we inoculated two V.
unguiculata cultivars, cultivar 1 and cultivar 2. The roots of one-week old plants were trimmed
and dipped for one minute in inoculum; negative controls were dipped in 0.1% water agar. For
both cultivars, isolates from cowpea caused symptoms one week after inoculation and by 65
days, 100% of plants were severely stunted and yellow (2/4 isolates). Of note, one isolate only
caused severe symptoms in cultivar 2, suggesting that there is some variation in genetic
resistance. Disease symptoms did not develop following inoculation with one isolate from
cowpea and one from tomato or in negative controls. Yield impacts followed similar trends, in
which pod biomass was less than the negative control plants. Fusarium falciforme was re-
isolated from the symptomatic plants. These results provide the first evidence that F. falciforme
is a pathogen of V. unguiculata. Further studies are needed to more comprehensively document
symptoms and name this disease, as well as to evaluate management options.
131
3. Undergraduate Student
THE EFFECT OF SALINITY ON NITROGEN ACQUISITION AND
BIOLOGICAL NITROGEN FIXATION OF ALFALFA
Amanda Cox1, Chloe Dugger1, Hossein Zakeri1, Sharon E. Benes2, Daniel H. Putnam3
1 California State University, Chico; 2 California State University, Fresno; 3 University of
California, Davis
Contact: Hossein Zakeri, CSU Chico, 400 W. 1st St., Chico CA, 95929
530-898-5753; [email protected]
Alfalfa (Medicago sativa) is a perennial legume crop, which obtains most of its nitrogen (N)
through biological nitrogen fixation (BNF). California has led the country in alfalfa production
for many years. However, increasing levels of salt in water and soil in major forage production
areas such as the San Joaquin Valley has raised concerns over the future of alfalfa production in
the state. In this ongoing pot study, we are investigating the impact of three salinity solutions and
four N fertilizer levels on alfalfa BNF. Seeds were inoculated with a commercial rhizobia
inoculant and planted in plug trays in the greenhouse. Seedlings were transplanted into 5-gallon
buckets on May 31st filled with a mixture of soil, sand and peat moss in an open field. All plants
received macro- and micro-nutrients, plus equivalent to 30 kg ha-1 starter N at the planting. After
the first cut, plants have been watered with tap water, low salinity (EC=~5 ds/m) or high salinity
(EC= ~10ds/m) water with the saline solutions prepared using NaCl, Na2SO4, MgSO4, and
CaSO4. Plants also receive four levels of urea fertilizer (equivalent to 0, 30, 60, and 120 kg N ha-
1) with the first irrigation after each cut. Daily watering is based on the total plant
evapotranspiration and the pot field capacity to eliminate leaching. Results will be presented in
more detail including the yield, evapotranspiration, and δ15N comparisons to compare N
acquisition from biological N fixation vs. applied mineral N.
132
4. Undergraduate Student
POTENTIAL USE OF REMOTE SENSING IN VINEYARD WEED
MANAGEMENT
Cody Drake1, Luca Brillante2, Ming-Yi Chou3, and Anil Shrestha2
1Department of Plant Science, California State University, Fresno, CA; 2Department of
Viticulture and Enology, California State University, Fresno, CA; 3St. Supéry Estate Vineyards
and Winery, Napa, CA
Contact: Cody Drake, CSU Fresno, Department of Plant Science,
In recent years, remote sensing technology is being explored as a management tool in agricultural
cropping systems, including vineyards. However, the technology has not been explored adequately
for weed management. Early identification of critical zones by drones would enable site-specific
weed management and avoid broadcast application of postemergence herbicides in vine rows.
Therefore, the objectives of this study were to: i) evaluate high-resolution aerial images of weed
presence in a commercial vineyard as a tool to assess weed pressure, ii) select management zones
for site-specific weed management and correlate weed pressure next to a vine with vine vigor, iii)
test and ground-truth aerial images for weed identification.
The experiment was conducted in winegrape vineyard in Napa County, where inter-rows were
disked while under-vine weeds were mechanically managed multiple times during the growing
season. Aerial images were obtained by a drone equipped with a multispectral camera. Two
flight heights were tested: 30 and 10 m above the vineyard floor with a resolution of 0.5 cm px-1
and 1 cm px-1, respectively. Based on field NDVI, two management zones were identified and
data on percent weed coverage and dry biomass were taken at three different locations. Species
were also identified. For mapping and visualization, image mosaics were obtained with
DroneDeploy, and data were analyzed and modeled. Results showed that areas of weed presence
could be successfully identified by the drone images. Vine vigor was not correlated with the
density or biomass of the weeds. The resolution of the images was good enough for identification
of several weed species. It can be concluded that remote sensing with drones can aid in site-
specific weed management in vineyards.
133
5. Undergraduate Student
CONSTRAINING THE EFFECTS OF DISTURBANCE FACTORS ON
SOIL RESPIRATION EFFLUX
Seth Myrick, Garrett Liles
California State University, Chico
Contact: Seth Myrick, CSU Chico, 1301 Sheridan Ave., Apt. 21, Chico, CA 95926
916-717-3408; [email protected]
Annually, soils represent the largest flux of carbon between the land and the atmosphere, via
plant photosynthesis and plant/soil respiration. Soil respiration remains the least well-constrained
component of the global carbon cycle, and given its large contribution, accounting for its role is
imperative. The overarching objective of our work is to provide a data synthesis and literature
review of CO2 efflux and plant-soil impacts associated with management and disturbance on
California forest soils. This work will provide a baseline of information to support broader goals
at the core of the California Biopower Impacts Project (CBIP). CBIP is a research grant from the
California Energy Commission with the scope of creating a Life Cycle Assessment and carbon
emissions accounting tool that will allow stakeholders in California to evaluate the
environmental impacts of different bioenergy production pathways. The effects of disturbance
(especially agriculture and forest management) on soil properties and respiration are highly
variable depending on the mode of disturbance and its intensity. Using data from NASA’s
Global Soil Respiration Database and reviewed literature, we are quantifying the variable
impacts of harvesting residual biomass on soil CO2 efflux, soil health, and long term site
productivity. Outside of the soil CO2 efflux data we synthesize, which will help to inform CBIP
carbon accounting efforts, areas of interest for the literature review include: erosion, compaction,
and structural changes from disturbance, C/N flux and changes to nutrient pools, soil biological
response to residual biomass harvest, and retaining soil fertility post-biomass harvest. Our
personal end goal for this work is to start meaningful discussions and policies concerning
sustainable land management in California agroecosystems, especially in forestry.
134
6. Undergraduate Student
THE EFFECTS OF WATER STRESS PRECONDITIONING ON HEAT
AND DROUGHT TOLERANCE OF CORN IN NORTHERN CALIFORNIA
Miriam Pacheco, Amanda Cox, Chloe Dugger, Hossein Zakeri
California State University, Chico
Contact: Hossein Zakeri, CSU Chico, 400 W. 1st St., Chico CA, 95929
530-898-5753; [email protected]
Corn is a warm-season crop that is grown during the summer when risk of prolonged drought
and heat stress, in most US states, is high. Agronomic practices that can reduce the negative
impacts of these abiotic stress factors can maintain high yield. In this experiment, we are
studying the effects of water stress preconditioning on yield and some physiological traits of corn
under field conditions. The technique involves exposing young plants to a stress in order to
stimulate long-lasting resistance to drought and heat stress The treatments included 1) fully
watered control, 2) primed, 3) primed and drought stress at flowering, and 4) drought stress at
flowering. Plants in the primed treatment did not receive water for two weeks from the V2 stage,
and plants under stress at flowering did not receive water for two weeks from the tassel stage.
The treatments were arranged in completely randomized design in four replications. The plots
received 30 mm water every 4-6 days based on the soil moisture.
The preliminary results show that the prime treatment reduced corn leaf surface area by 68%.
However, resumed irrigation increased the leaf surface area of the primed plants. Before
applying the second drought stress at flowering, primed plants had 10% less leaf surface area
than non-primed plants. The onset of priming treatment significantly reduced the corn stomatal
conductance (50% reduction), but stomatal conductance of the primed plants was gradually
recovered after resuming the irrigation and reached the conductance of non-primed plants.
Results will be presented in more detail, including the yield variations in response to the
treatments.
135
7. Undergraduate Student
NITROGEN USE EFFICIENCY AND WATER USE EFFICIENCY OF
AUTOMATED DRIP IRRIGATED TOMATOES SUBJECTED TO FOUR
FERTILIZER RATES
Lily Reyes Solorio, Tiffany Frnzyan, Anthony Mele, Florence Cassel S., Dave Goorahoo,
Charles Cochran, and Janet Robles
California State University, Fresno
Contact: Lily Reyes Solorio, CSU Fresno, Department of Plant Science and Center for Irrigation
Technology, 2415 E. San Ramon Ave., M/S AS72, Fresno, CA 93740-8033
(559) 278-2861
Precision irrigation techniques have shown to improve nitrogen (N) uptake and increase
irrigation efficiency. The objectives of our study were to assess the effects of various irrigation
scheduling methods and N fertilization rates on nitrogen use efficiency (NUE) and water use
efficiency (WUE) of drip irrigated processing tomatoes. The field study was conducted at
California State University, Fresno, on a sandy loam soil characterized by poor infiltration. The
experimental design was a strip block with four replicates of four irrigation scheduling strategies
(grower standard, 100% and 70% of evapotranspiration (ET), and soil moisture sensors) and four
N fertilizer rates (0, 60, 120, and 180 lbs N/ac, applied as CAN17). The grower standard
irrigation method represented the control; the ET method consisted in applying water based on
daily reference evapotranspiration data obtained from a nearby weather station coupled with
daily crop coefficients, at 100% and 70% of water requirements; the soil moisture sensor method
relied on sensors installed at 6” below the soil surface. Processing tomatoes were planted during
the spring of 2017 and harvested in the summer. Irrigation and fertilizer treatments did not affect
total yields. The 70% ET irrigation treatments had the highest WUE values at 0.061 tons per
acre per millimeter of water applied. The 60 lbs N/ac treatment had the highest NUE values at
0.40 tons per acre per pound of nitrogen applied.
136
1. Masters Student
USE OF IN-SEASON PROXIMAL SENSING DEVICES TO INDICATE
CORN N AND WATER DEFICIENCY
Taylor Becker1, Mark Lundy1, Michelle Leinfelder-Miles2
1University of California, Davis; 2University of California Cooperative Extension, San Joaquin
County
Contact: Taylor Becker, UC Davis, 1 Shields Ave, Davis, CA 95616
802-377-1723; [email protected]
The purpose of this project is to relate nitrogen (N) and water-induced differences in corn
productivity to canopy and leaf reflectance measured by proximal sensing devices, and
determine if those values indicate crop N deficiency that will affect final yields. Water
treatments included 25%, 50%, and 100% evapotranspiration (ET) until the blister (R2) stage
after which all received 100% ET. Nitrogen treatments included 28, 118, and 236 kg N/ha. One
biomass harvest occurred at R2 with corresponding treatment-specific proximal sensing
measurements at leaf, canopy and field scales. Silage and grain yields were determined at R5 and
full maturity (R6), respectively. Silage yields measured 23,886 kg/ha of dry matter in the
maximum water and N treatment (20.0 inches applied, 236 kg/ha N), 19,231 kg/ha in the low
water treatment (10.8 inches applied), and 18,771 kg/ha in the low N treatment (28 kg/ha N).
Grain yields were 16,549 kg/ha in the maximum water and N treatment, 11,737 kg/ha in the low
water treatment and 9,908 kg/ha in the low N treatment. Biomass yields measured at R2
correlated with silage yields (r2=0.58, p<0.001). Cob yields at R2 correlated with grain yields
(r2=0.62, p<0.001). Several proximal sensing variables measured at R2 correlated with plant
productivity outcomes. Chlorophyll concentration estimated in upper leaves via an atLEAF
chlorophyll meter correlated with R2 cob yields (r2=0.67, p>0.001) and final grain yields
(r2=0.67, p<0.001). Green Normalized Difference Vegetative Index (GNDVI) measured above
the canopy with a UAV-mounted multi-spectral camera correlated with cob yield at R2 (r2=0.69,
p<0.001) and grain yield (r2=0.62, p<0.001). Results indicate that N and water-induced
differences in corn productivity can be indicated in-season at various spatial scales by reflectance
tools.
137
2. Masters Student
STUDY OF POTENTIAL INTERACTIONS BETWEEN TWO COTTON
PATHOGENS, FUSARIUM OXYSPORUM F. SP. VASINFECTUM (FOV)
AND RHIZOCTONIA SOLANI
Josue Diaz1, Robert B. Hutmacher2, Margaret L. Ellis1
1Department of Plant Science, California State University, Fresno, USA; 2Univ. of California,
Shafter Res. and Ext. Cent., 17053 N. Shafter Ave., Shafter CA, USA;
Contact: Josue Diaz, CSU Fresno, Department of Plant Science, 2415 E. San Ramon,
Fresno, CA 93740
805-878-4708; [email protected]
Fusarium oxysporum f. sp. vasinfectum (FOV) and Rhizoctonia solani are two prevalent
soilborne fungal pathogens of cotton. First identified in California in 2001 and Texas in 2017,
FOV race 4 can be a virulent wilt pathogen to susceptible varieties. R. solani is a seedling
disease that causes damping off and root rot. FOV and R. solani have been observed causing
disease in the same fields and there has been interests on the potential interactions and their
impact on disease development. Therefore, the purpose of this study was to evaluate possible
interactions between FOV race 4 and R. solani in a co-inoculation assay in the greenhouse. The
planting material included one FOV race 4 susceptible line and four resistant lines. The FOV
race 4 isolate TM-13 and R. solani isolate R1 were used to prepare oat-infested inoculum.
Infested oats were mixed with potting soil and cotton seeds were planted into one of the
following treatments; FOV race 4 alone, R. solani alone, co-inoculation with both pathogens, and
non inoculated oats were used as a control. At five weeks, final stand counts were taken and
plants were rated using an ordinal rating scale for foliar and vascular symptoms (1= no disease,
5= dead). There was a significant difference for final stand count, foliar and vascular symptoms
among fungal treatment (P<0.0001). There was no difference between varieties. These results
indicate a possible additive effect on disease development of cotton when the two pathogens are
present simultaneously.
138
3. Masters Student
PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF
FUSARIUM OXYSPORUM F. SP. VASINFECTUM (FOV) ISOLATES AS
SEEDLING AND WILT DISEASE PATHOGENS OF COTTON
Josue Diaz1, Robert B. Hutmacher2, Mauricio Ulloa3 Margaret L. Ellis1
1Department of Plant Science, California State University, Fresno, USA; 2Univ. of California,
Shafter Res. and Ext. Cent., 17053 N. Shafter Ave., Shafter CA, USA; 3USDA-ARS Plant Stress
and Germplasm Development Research, Lubbock, TX, USA
Contact: Josue Diaz, CSU Fresno, Department of Plant Science, 2415 E. San Ramon,
Fresno, CA 93740
805-878-4708; [email protected]
Fusarium oxysporum f. sp. vasinfectum (FOV) race 4 is a virulent wilt pathogen of cotton that
has also been known to cause damping off and seedling mortality in infested fields. To better
assess disease impacts under California field conditions, more needs to be known about the
genotypic and phenotypic diversity of FOV isolates. In this study, sixteen isolates were
genotyped using two sets of FOV race 4 specific primers. DNA sequencing of the translation
elongation factor, phosphate: H+ symporter, and β-tubulin genes were also completed for
representative isolates. Results identified twelve isolates as FOV race 4, while four of the isolates
could not be clearly identified as FOV race 4 using specie specific primers. To phenotypically
characterize isolates, a rolled towel assay was used to test seedling infection capabilities and a
root dip inoculation assay was used to determine their ability to produce wilt symptoms. Plant
material for these assays included the FOV race 4-moderately resistant Upland cultivar FM-2334
and susceptible Pima cultivar PHY-830. For the rolled towel assay seeds were individually
inoculated with 100 µl of a 1×106 conidia/ml suspension. At ten days, seedlings were rated using
a disease severity index (DSI) and ordinal rating scale. There was a significant difference for
isolate and variety (P<0.0001) for the DSI and ordinal rating. For the root dip assay seedlings
were submerged in a 1×106 conidia/ml suspension, transplanted, and placed in a greenhouse. At
six weeks, plants were evaluated for foliar symptoms and vascular discoloration. There was a
significant difference among isolate and variety (P<0.0001) for foliar and vascular symptoms.
Based on our results, all isolates were able to produce seedlings and wilt symptoms on cotton.
139
4. Masters Student
LYSIMETRIC DETERMINATION OF EVAPOTRANSPIRATION FOR
DRIP-IRRIGATED ONIONS
Aldo Garcia, Shawn Ashkan, Florence Cassel, Anthony Mele, and Dave Goorahoo
California State University, Fresno
Contact: Aldo Garcia, CSU Fresno, Department of Plant Science & Center for Irrigation
Technology, 2415 E. San Ramon Ave. M/S AS 72, Fresno, CA 93740
559-278-2861; [email protected]
Accurate estimation of crop water requirements (CWR) is essential to optimize water use
efficiency and develop efficient irrigation scheduling practices. This is particularly important in
California where frequent droughts have accentuated the need to conserve water and improve on-
farm water management. The most accurate method to determine CWR is with precision
weighing lysimeters, which measure actual crop evapotranspiration (ETa). Thus, the objectives
of this study were to determine ETa data, develop new crop coefficients (Kc), and evaluate the
relationship between Kc and crop fractional ground cover (Fc) for processing onions grown under
drip irrigation. Daily measurements of crop ET and ETo were collected on a clay loam soil using
the crop and grass lysimeter facilities available at the University of California Westside Research
and Extension Center in Five Points, CA. Weekly measurements of crop ground cover were also
performed to derive relationships between Kc and fractional cover. Results from our first year
study indicated that peak ET for onion averaged 7.5 mm/day, while midseason Kc was 1.14. A
strong correlation was also observed between crop Kc and fractional ground cover (Fc), with an r2
> 0.90. Such findings are important to schedule effective irrigation cycles and optimize the use
of water resources.
140
5. Masters Student
CULTIVAR AND NUTRIENT MANAGEMENT EFFECTS ON NUTRIENT
USE EFFICIENCY IN STRAWBERRIES
Kamille Garcia-Brucher, Charlotte Decock, Kelly Ivors, Gerald Holmes
California Polytechnic University, San Luis Obispo
Contact: Kamille Garcia-Brucher, California Polytechnic University, San Luis Obispo,
1 Grand Ave., San Luis Obispo, CA 93407
310-717-1863; [email protected]
The intensively managed strawberry cropping systems have been identified as high-risk non-
point sources of nitrate (NO3-) pollution of ground and surface waters. Motivated by rising
environmental concerns and pending legislative restrictions, there is an increasing interest from
strawberry growers and stakeholders in the strawberry industry to improve the sustainability of
their nitrogen (N) management. The application of controlled release fertilizers (CRFs) in fall as
a pre-plant fertilizer is common practice in California strawberry cultivation, based on the idea
that the CRF will slowly release plant available nutrients over the course of the winter season.
Recent studies have shown much of the CRF N is released before plant N uptake is significant.
This suggests that the CRFs commonly used by strawberry growers are unlikely an effective
source of nutrients for the strawberry crop. As composts are known to have slower release
patterns compared to what has been observed for the CRFs, compost might be a viable substitute
for early season nutrient delivery to strawberry crops. A field experiment at the Cal Poly
Strawberry Center beginning in September 2018 aims to observe soil and plant N dynamics
comparing three pre-plant fertilizer strategies among four strawberry cultivars. Fertilizer
treatments include 100 lbs N/acre of CRF, 100 lbs N/acre of compost and a control with no pre-
plant fertilizer. Soil pore water and plant samples are collected and analyzed to determine soil N
availability, plant biomass, plant N uptake, and N use efficiency. Early-season samples are
currently being analyzed. We hypothesize that differences in soil N availability between fertilizer
treatments will affect nitrogen use efficiency, without impacting plant N uptake and yield.
141
6. Masters Student
EVALUATING SOIL SALINITY AS A RISK FACTOR FOR FUSARIUM
WILT OF TOMATO
Beth Hellman, Cassandra Swett
University of California, Davis
Contact: Beth Hellman, UC Davis, Department of Plant Pathology, One Shields Ave.,
Davis, CA 95616
301-919-3557; [email protected]
California produces over 95% of all processing tomatoes grown in the United States. Fresno
County is the production hub, representing 1/3 of the market. Fusarium wilt of tomato, caused by
the fungal pathogen Fusarium oxysporum f. sp. lycopersici race 3 (Fol R3), is a devastating
disease that decreases tomato marketability and yield; management relies primarily on use of
resistant cultivars (F3). As a stress-induced disease, there is concern that high salt levels, as
occurs in Fresno County soils, might increase Fusarium wilt risk and compromise resistance. To
evaluate this possibility, we examined Fusarium wilt development in highly susceptible, tolerant
and resistant cultivars under salt and non-salt conditions, comparing performance in an infested
and a non-infested field. At 64 days post-transplant, Fusarium wilt symptoms were observed in
the infested field in 4.17% and 49.87% of tolerant and highly susceptible F2 cultivars
(respectively) under saline treatment compared with 0%and 52.05% incidence in the non-saline
soils. At the end of the growing season, Fusarium wilt was observed in 100% of highly
susceptible F2 cultivars (P > 0.05) and 8.3% of tolerant cultivars. Fusarium wilt developed in
two of the three resistant (F3) cultivars (3.70 – 6.67% of plants) in the saline treatment; no
symptoms developed in non-saline soils. Yields and fruit quality were similar across all
treatments (P > 0.05). These results indicate that salinity increases risk of Fusarium wilt
development in both susceptible and resistant cultivars, and that salinity stress may be
compromising the effectiveness of F3 resistance. Future work will attempt to develop strategies
for co-management of Fusarium wilt and soil salinity.
142
7. Masters Student
WATER USE EFFICIENCY OF AUTOMATED ET AND SENSOR BASED
DRIP IRRIGATED BROCCOLI SUBJECTED TO FOUR FERTILIZER
RATES
Anthony Mele, Dave Goorahoo, Florence Cassel S., Aldo Garcia
California State University, Fresno
Contact: Anthony Mele, CSU Fresno, 2415 E. San Ramon, Fresno, CA 93740-8033 M/S AS72
559-278-2861; [email protected]
Improper irrigation scheduling can adversely affect plant growth, increase disease prevalence,
leach available nitrogen below the root zone, and ultimately reduce production profitability.
Continuous, real-time monitoring of soil and atmospheric data has proven to be an effective
method in minimizing irrigation error at the field scale. Furthermore, recent advances in
precision irrigation technology has made real-time monitoring for irrigation a viable option for
growers. The objectives of this field study were to evaluate the interaction between N-fertilizer
rates and irrigation scheduling on yield and irrigation water use efficiency (iWUE). The
experimental design was a split plot with four replications. Irrigation served as the main
treatment with three different scheduling regimes: 1. automated soil moisture sensor (SMS) 2.
automated water balance (ET) and 3. standard grower practice (manual). Four fertilizer rates
served as the sub treatments: 0 lb N/ac control, 60, 120, and 180 lb N/ac applied as CAN-17.
Fertilizer rates did have an effect on broccoli weights (P = 0.000). The 180 lb N/ac rate had the
highest fresh harvest head weights compared to all other fertilizer treatments. Irrigation
scheduling did not affect head weights at P = 0.316, and no interaction was detected between
irrigation schedule and nitrogen rate. The SMS based treatments had the highest (iWUE) values
with a 39% and 30% reduction in water applied compared to the ET and manual treatments,
respectively. These preliminary results suggest that sensor based irrigation scheduling can
produce yields equivalent to those under traditional grower practices with a substantial savings in
water applied.
143
8. Masters Student
GLUTATHIONE LEVELS AS AN INDICATOR OF OXIDATIVE STRESS
IN AIRJECTION IRRIGATED TOMATOES: METHODOLOGY &
PRELIMINARY RESULTS
Chaitanya L. Muraka, L. Dejean, D. Goorahoo, F. Cassel S., C. Cochran, A. Garcia, J. Robles
California State University, Fresno
Contact: Chaitanya Muraka, CSU Fresno, Plant Science Department, 2415 E. San Ramon,
Fresno, CA 93740-8033 M/S AS72
559-278-2861; [email protected]
AirJection® is a type of irrigation in which the ambient air is sent through sub-surface drip
irrigation (SDI) tape via a venturi injector. This modification in the SDI system enhances
respiration to plant roots, improves stomatal conductance and can potentially reduce oxidative
stress, caused by the Reactive Oxygen Species (ROS). Of all the anti-oxidants, Glutathione
(GLU) is a good indicator of stress as the ratio of reduced (GSH) and oxidized (GSSG) fluctuates
when stress occurs in the plant i.e. a lower level of GSH: GSSG indicates reduced stress in plants
and vice-versa. The overall goal of the study was to characterize the levels of Oxidative stress in
the plants subjected to aerated and non-aerated irrigation systems. In this phase of the study the
objective was to quantify the relative amounts of both reduced (GSH) and oxidized (GSSG)
forms of glutathione in tomatoes using fluorometric assay. Earlier studies using a DTNB-based
colorimetric assay (Promokine) indicated that Airjection triggered an increase in GSH in leaves
and fruits. During 2018 mid-season, tomatoes collected from aerated and non-aerated sites
showed average total glutathione contents of 2353.3 μg/ml and 3014.18 μg/ml respectively. In
addition, the average GSH levels in airjection (12.6 μg/ml) was 1.5 times less than in the non-
aerated plots (18.6 μg/ml), which contrasted with the previous studies. However, the GSH:
GSSG ratios were 1.2 times lesser for aerated (0.006) and non-aerated (0.0084) tomatoes in
accordance with the earlier results. These preliminary findings justify the further determination
of GSH, GSSG and GST in the samples of leaves and fruits.
144
9. Masters Student
THE EFFECTS OF MIDSEASON DRAINAGE ON GREENHOUSE GAS
EMISSIONS AND YIELD IN CALIFORNIA RICE SYSTEMS
Henry Perry, Daniela Carrijo, Bruce Linquist
University of California, Davis
Contact: Henry Perry, UC Davis, 387, N Quad, Davis, CA 95616
310-775-1357; [email protected]
Rice (Oryza sativa L.) cultivation is a tremendously important component of global food
security, yet it is also responsible for a significant portion of agricultural greenhouse gas (GHG)
emissions and land water use. Midseason drainage of rice fields is known to decrease grain
arsenic concentrations, GHG emissions, and land water use, but its effect on grain yield is quite
variable. In this two-year study, we aimed to measure the effect of severity and timing of
midseason drains on GHG emissions and yield. In 2017 treatments included High (HS), Medium
(MS), and Low Severity (LS) drains that started 34, 37, and 40 days after seeding (DAS) for a
duration of 11, 8, and 5 days, respectively. 2018 treatments included one LS drain that started 44
DAS and lasted 5 days in addition to two HS drains, one of which started 37 DAS (lasting 11
days) and another that started 45 DAS (lasting 14 days). We measured methane (CH4) and
nitrous oxide (N2O) emissions, soil nitrogen, grain yield, and yield components. In order to
monitor drain severity, we measured several soil moisture parameters including volumetric water
content, perched water table, gravimetric water content, and soil water potential. Aside from the
HS drain in 2017, grain yield of drainage treatments did not significantly differ from that of
continuously flooded (CF) control treatments. Midseason drainage also reduced seasonal CH4
emissions by 8-67%, and N2O emissions were quite minor (average = 0.018 kg N2O-N/ha), as
they accounted for only 0.2% of the seasonal global warming potential across all drainage
treatments. These results indicate that midseason drainage is capable of mitigating GHG
emissions associated with rice cultivation without sacrificing grain yield.
145
10. Masters Student
EFFECTS OF DORMANT DROUGHT STRESS ON ALMOND (PRUNIS
DULCIS) BLOOM; OR, WHAT IF IT DOESN’T RAIN IN THE WINTER?
Michael Rawls, Ken Shackel, Jiong Fei
University of California Davis
Contact: Michael Rawls, UC Davis, 1 Shields Ave., Davis, CA 95616
Little is known about the effects of winter drought stress on deciduous tree crops. With the
increasing likelihood of winter drought events, it is vital to determine if trees experience water
stress during dormancy and if so, when is the most efficient time during winter to irrigate. More
research is needed to understand the influence of winter drought on bloom time, chill
requirements, and yield potential. If winter irrigation is found to be unnecessary, water could be
saved and water use efficiency increased, and if irrigation if found to be beneficial, yields could
be increased. The objective of this research is to investigate the effects of winter drought stress
on almond flower bud development. In the winters of 2016/2017 and 2017/2018, drought stress
was applied to potted trees in order to quantify the effects. Our data indicates that winter drought
stress in Almond (Prunis dulcis) can cause a bloom delay but does not seem to otherwise effect
flower bud development nor leaf out dates. The stress treatments had physiological and
developmental effects in our potted tree study. Hence dormant drought stress can cause
significant effects in orchards and should be studied further under field conditions.
146
11. Masters Student
EFFICACY TRIALS OF NEW DORMANCY-BREAKING TREATMENTS
IN PISTACHIOS
Daniel Y.P. Syverson, Masood Khezri, John Bushoven, Louise Ferguson, Gurreet Brar
California State University, Fresno
Contact: Daniel Syverson, CSU Fresno, 2658 E. Alluvial Ave #206, Fresno, CA 93720
559-770-1656; [email protected]
In recent years, pistachio yields in California have been harmed by low-chill winters. Low-chill
winters can result in delayed and uneven dormancy release, resulting in greater exposure to late-
season pest pressure from navel orangeworm. Low winter chill can also create asynchrony
between male and female bloom in this dioecious species. Pistachio growers thus seek
management options to advance nut development while maintaining good pollination synchrony.
We are using both field trials and growth chamber experiments to assay candidate dormancy-
breaking agents (DBAs) for late-winter application to pistachio that can advance leaf-out and
compress the bloom window without adverse yield effects. We compared ethephon, GA3, and
AVG sprays near endodormancy completion with grower standard treatments of horticultural oil
and water. We monitored bud respiration, bloom phenology, yield and nut quality components.
Ethephon and GA3 both advance bloom, but only GA3 compresses the bloom window. AVG
retards bloom and may interfere with the accumulation of heat. Bud respiration rates 3 weeks
before bloom reflected the observed bloom order, but DBA-induced increases of respiration
immediately after application were uncorrelated with effects on bloom and should generally be
considered a side effect unless part of a known mode of action. The results of this research may
be used to support registration of new products for dormancy management in pistachio and other
high-chill perennial crops.
147
12. Masters Student
INTERACTION OF AVG WITH VARYING NITROGEN APPLICATION
RATES IN RELATION TO YIELD AND QUALITY IN ALMONDS
Travis Woods, Gurreet Brar
California State University, Fresno
Contact: Gurreet Brar, CSU Fresno, 2415 E San Ramon, M/S AS72, Fresno, CA 93740
559-278-4119; [email protected]
Almond kernels are large nitrogen sinks and it has been shown that almond trees cannot meet the
nitrogen demands in-season. Developing kernels compete with adjacent leaves for N, reducing
leaf N, thus reducing photosynthetic capacity and creating a resource deficit leading to ‘June’
Drop. Early supplemental nitrogen applications may mitigate ‘June’ Drop. Application of plant
growth regulator Aminovinylethoxyglycine (AVG) is known to increase fruit set. This study
aims to combine AVG with varying rates of supplemental nitrogen to induce a higher nut set,
mitigate ‘June’ drop, and bring an increased nut set to yield. The experimental plot is located in a
fully mature almond orchard in Biola, CA, planted at 22’ X 15’ spacing. The experiment was
designed as a Random Complete Block Design with factorial. Three rates of nitrogen were
applied through chemigation, with and without AVG. Nitrogen rates were determined using the
model developed by Brown and associates at the University of California. Applied nitrogen rates
were as follows: N1(100%) =250 lbs., N2(112%) =280 lbs., N3(125%) =312 lbs. AVG was
applied with a foliar spray at a rate of 333 g/acre during 50% bloom. Blossom counts, nut set,
and ‘June’ drop counts were taken on last meter of selected branches in all four quadrants.
Leaves were sampled from spurs bearing two fruits and non-bearing spurs, as well as the two
fruits from the bearing spurs. Samples were taken at various phenological stages. 2018 data did
not show statistically significant differences in yield, but nut set was significant. AVG treatments
showed a significant increase in the number of double nuts, however, differences in fresh and dry
weights of kernel and hull were not significant.
148
1. PhD Student
EVALUATING EFFECTS OF SUBSTRATE AND WATER USE
REDUCTION POTENTIAL ON DISEASE RISK IN CONTAINERIZED
TOMATOES
Justine Beaulieu, Bruk Belayneh, Andrew Ristvey, John Lea-Cox, Cassandra Swett
University of California, Davis
Contact: Justine Beaulieu, UC Davis, Department of Plant Pathology, 1 Shields Avenue,
Davis, CA 95616
301-661-1386; [email protected]
As growers face increasing constraints on water use, understanding the disease risks associated
with deficit irrigation (DI) is paramount. Previous studies with Phytopthora capsici root and
crown rot in tomato indicated that DI increases latent infection and disease risks. This work
evaluates how differences in soil/substrate influence DI-associated root and crown rot risk in
processing tomato Heinz 8504. We hypothesized that substrates with greater water holding
capacity (WHC) would present a lower disease risk under DI, due to fewer drying cycles and less
plant stress. We evaluated three substrates: 1) Bark (Fafard #52 Metro Mix, low WHC), 2)
Hydrafiber (medium WHC), and 3) Peat (LC1, high WHC), and two irrigation schemes: 1)
“Saturated” (45% volumetric water content (VWC) and 2) “Deficit” (28% VWC in peat and
hydrafiber, 30% VWC in bark). Shoot growth was significantly lower under deficit vs. saturated
conditions across all treatments. In inoculated plants, shoot biomass was significantly lower
under deficit vs. saturated in all substrate treatments. In the peat, crown rot incidence was
significantly greater under deficit vs. saturated conditions, but there was no effect of irrigation on
% root necrosis. In bark, % root necrosis was significantly lower under deficit irrigation and in
the hydrafiber % root necrosis was significantly greater under deficit irrigation. Under deficit
irrigation, % root necrosis was greatest in hydrafiber, followed by peat and bark. These
preliminary results suggest that the substrate/soil environment influences the risk of deficit
irrigation. In controlled environments, bark appeared to have the lowest risk and hydrafiber the
greatest. More work is needed to elucidate the details of that relationship and to translate the
experiments to field soils.
149
2. PhD Student
A SEAT AT THE TABLE: CALIFORNIA FARMERS SPEAK UP ON
SGMA
Alyssa Jill DeVincentis, Jessica Rudnick, Linda Estelí Mendez Barrientos
University of California, Davis
Contact: Alyssa Jill DeVincentis, UC Davis, One Shields Ave, Dept. LAWR PES 1111,
Davis CA 95616
732-275-4027; [email protected]
California’s agricultural sector, a major groundwater user, finds itself in the midst of the
implementation of the Sustainable Groundwater Management Act (SGMA). The Sustainable
Groundwater Management Act was passed in 2014 in the midst of a statewide severe drought
and requires that all overdrafted groundwater basins across California to form local groundwater
sustainability agencies (GSAs) and adopt groundwater sustainability plans (GSPs) by 2020. The
extent of grower participation and involvement in GSAs will be a key component to the
development of GSPs and the agricultural sector’s water access in coming decades. We collected
data on grower participation in SGMA through 27 semi-structured interviews with growers
across California in several priority groundwater basins between 2016 and 2018. Interview
questions asked about the growers’ experiences with the recent 2011-2015 California drought,
their understanding of SGMA, involvement in GSAs, and concerns for future agriculture and
water availability. Our analysis investigates relationships between perceptions and experiences
with drought, access to water resources, and participation in the SGMA water governance
process. Our results show that the drought had a variable impact on growers across the state,
impacting their water access and adoption of drought adaptation strategies differently. However,
these experiences did not predict their knowledge and participation in SGMA. Rather, growers’
participation in SGMA appears to be a factor of access to resources and financial and human
capital. These results shed light on the potential lack of diverse representation of agriculture in
the SGMA process and highlight an area that deserves close attention as groundwater
management plans are developed.
150
3. PhD Student
NITROGEN DYNAMICS OF ORGANICALLY FERTILIZED HEIRLOOM
TOMATOES
Patricia Lazicki1, Margaret Lloyd2, Daniel Geisseler1
1University of California, Davis; 2University of California Cooperative Extension, Yolo,
Sacramento & Solano Counties
Contact: Patricia Lazicki, UC Davis, Dept. of Land, Air and Water Resources, One Shields
Avenue, Davis, CA, 95616
626-298-9066; [email protected]
Organic growers have the technology to match the timing and amount of nitrogen (N) applied
with the needs of their crop but lack reliable data on temporal N release from organic
amendments and uptake by plants. The project’s goal was to develop seasonal N uptake curves
of a popular heirloom tomato variety and assess temporal availability of N from several types of
organic amendments. We tracked the growth, yields and N uptake of Brandywine tomatoes
grown with different amendments in 2017-2018 on commercial organic fields in the Capay
Valley and in a replicated field trial at UC Davis. We used controlled lab incubations in two
different soil types to assess potential N release from 19 different composts and fertilizers (liquid
and granular) used by local organic tomato growers. Our lab and field results show that
amendment N release varied widely, from slight immobilization of soil N to almost 100%
availability, but was predictable based on the amendment carbon to N ratio. The N release
dynamics were not significantly affected by different soils. Total N uptake varied with the site,
amount of available N in the soil and overall plant vigor and site-year averages ranged between
96 and 220 lbs N/acre. N removed with the harvested fruit averaged 2.30 and 2.55 lbs/ton fresh
fruit in 2017 and 2018, respectively. Tomato N demand was highest between the flowering and
the first harvest, with an average uptake rate of 3.5 lbs N/acre/day during peak growth periods.
151
1. Non-Students
SOIL AND TISSUE N CYCLING IN CORN-WHEAT SILAGE ROTATION
ON MANURED SOIL
Jorge Angeles, Bob Hutmacher, Till Angermann, & Nicholas Clark
California Cooperative Extension Tulare & Kings County, West Side Research and Extension
Center
Contact: Jorge Angeles, CSU Fresno, 1338 E San Ramon Ave APT H, Fresno, CA 93710
559-940-8549; [email protected]
In the San Joaquin Valley (SJV) of California, ground water quality is negatively impacted by
inefficient crop use of nitrogen (N) in fertilizer and manure in crops. The 2013 Revised Dairy
General Order mandates that N applied to crop fields receiving manure or process waste water
not exceed 1.4 times the N removed in harvested plant parts. A research program was started by
the Central Valley Dairy Representative Monitoring Program (CVDRMP) to evaluate the
impacts of irrigation water and N inputs. The main focus of the program is on the breadth of
environmental and management practice variables representative of SJV dairies. Therefore, a
study was conducted in 2017-19 at a heifer ranch located in the Tulare, CA. An objective of this
study was to examine the seasonal N accumulation and soil mineral N content of a silage corn
and wheat rotation. The three treatments were Manure Only (~18.5 tons/ac, ~70% DM, ~1.5%
N), Manure + fertilizer (100 lbs N/ac from UAN32) and a 0 N control treatment. The
experimental design was a randomized complete block design. Silage corn was grown and
rotated with silage wheat in the winter. Tissue, soil and irrigation water samples were taken in
the growth season of each crop to create an N budget, and monitor N tissue accumulation and
soil mineral N content. Results showed that the seasonal N accumulation and soil mineral N
content were similar between the three treatments in the silage corn but both of the manure
treatments had a higher N accumulation and soil mineral N in the wheat crop. The cumulative
soil nitrate was higher in the Manure + fertilizer treatment and increased with depth.
152
2. Non-Students
COVER CROP CULTIVAR ADAPTATION TO THE CALIFORNIA
CENTRAL VALLEY
Valerie Bullard
USDA-Natural Resources Conservation Service, Lockeford Plant Materials Center
Contact: Valerie Bullard, USDA-NRCS, 21001 N. Elliott Rd., P.O. Box 68,
Lockeford, CA 95237
209-867-3101; [email protected]
Cover crops are increasingly used in agriculture and provide numerous benefits including
improved soil health, enhanced nutrient cycling and retention, increased water holding capacity,
and competitive suppression of weeds. Other benefits may include lower use requirements for
fertilizer and herbicide, and greater drought tolerance. There are numerous cover crop choices
available on the market, but little is known about the adaptability of certain cultivars and
varieties to specific regions in the United States. In this national trial, eight species and 59
different cool season cover crop cultivars were evaluated for adaptation to the California Central
Valley at the Lockeford Plant Materials Center. The purpose of this nationwide trial was to
evaluate growth characteristics and production attributes of commercially available cultivars and
local sources of selected cover crops. Evaluations included germination/field emergence, winter
hardiness, beginning of regrowth, bloom and flowering period, plant height, disease and insect
resistance, canopy cover, aboveground biomass, and total nitrogen content. This summary
includes two years of evaluation data and observations at the Lockeford trial location.
Performance was assessed, and most of the cover crop species and cultivars evaluated in this trial
performed well in the Central Valley of California. However, cultivar choice can make a big
difference in the agronomic benefits of a cover crop. Trends were seen in both growth
characteristics and production in terms of bloom time and flowering period, nitrogen content,
and biomass production between cultivars. Effective cover crop cultivars will need further
evaluation in relation to specific farming operations to estimate their compatibility and success
with different agricultural systems and practices in California.
153
3. Non-Students
EFFECTS OF IRRIGATION AND NITROGEN FERTILIZATION
REGIMES ON WATER USE AND NITROGEN USE EFFICIENCIES OF
SORGHUM AND CORN
Florence Cassel, Anthony Mele, Janet Robles, Lily Reyes Solorio, Tiffany Frnzyan, Dave
Goorahoo, Charles Cochran
California State University, Fresno
Contact: Florence Cassel, CSU Fresno, Department of Plant Science & Center for Irrigation
Technology, 2415 E. San Ramon Ave. M/S AS 72, California State University, Fresno, CA
93740
559-278-7955; [email protected]
Recent droughts in California have shown a renewed interest in producing forages that require
less water and can be grown on marginal soils. Compared to corn that is sensitive to water
shortages and soil salinity, sorghum is well known for its adaptability to poor quality soils and
water, as well as hot and arid environments with limited water supplies. Thus, the objective of
our study was to evaluate the tolerance of sorghum grown under various irrigation regimes and
nitrogen (N) fertilization rates, in comparison with corn that has traditionally been supplied as
forage for the dairy industry. The experimental design was a split block with the two crops
(sorghum, corn) and four replications of N rate as the main treatment (0, 75, 150, and 225 lb
N/ac) and irrigation as the sub-treatment (100% ET surface-drip, 70% ET surface-drip, and
100% ET flood). The experiment was conducted in the Central Valley of California during a
two-year period. Water Use Efficiency (WUE) and Nitrogen Use Efficiency (NUE), defined as
the crop yield per unit water or N fertilizer applied, respectively, were derived for each
treatment. With the exception of the 2017 sorghum harvest, the 100% ETc drip treatments had
the highest average yields. Although the deficit irrigated treatments experienced reduced yields,
the 70% ETc drip treatments maintained the highest WUE for both crops during both growing
seasons. The 75 lb N/ac treatments had the highest observed NUE values for both crops, except
for the 2018 sorghum harvest. The preliminary results suggest that sorghum grown under drip
irrigation can equal, and in some cases, exceed silage corn in yield, WUE, and NUE.
154
4. Non-Students
AGRONOMIC OVERVIEW OF NITROGEN MANAGEMENT PLANNING
RESULTS FROM THE IRRIGATED LANDS PROGRAM
John Dickey, Yohannes Yimam, Tim Hartz, Ken Cassman, Andrea Schmid, Jessica Crichfield
South San Joaquin Valley Management Practices Evaluation Program
Contact: John Dickey, SSJV MPEP, 4886 E. Jensen Avenue, Fresno, CA 93725
916-517-2481; [email protected]
Irrigated Lands Regulatory Program (ILRP) orders require Central Valley irrigators to complete
Nitrogen Management Plans (NMPs) for each crop. Nitrogen (N) applied and yield (for acreage
designated highly vulnerable) are reported to growers’ water quality coalitions, who in turn
summarize them for the Water Board. The South San Joaquin Valley Management Practices
Evaluation Program (SSJV MPEP) has analyzed 2016 NMP data from an agronomic perspective,
to examine the yield growers realize across a range of N application rates. The data also illustrate
commonly, occasionally, and rarely reported ranges of N application rates. For most crops, the N
balance (N applied minus N removed in the crop, and thus the N subject to storage and loss)
grows steadily as N application increases. This analysis is a helpful snapshot of what growers
reported in 2016, which may inform discussion about how to improve NMP data collection, and
perhaps about how best to balance profitability and environmental risk associated with N
fertilization of citrus.
155
5. Non-Students
ASSESSMENT OF ORANGE IRRIGATION AND FERTILIZATION BY
COMBINING GROWER OPERATIONAL RECORDS, ACTUAL
EVAPOTRANSPIRATION, SOIL, AND PLANT TISSUE DATA
John Dickey1, David Cehrs2, Michael Sowers1, Ken Cassman1, Thomas Harter3
1 South San Joaquin Valley Management Practices Evaluation Program; 2 Geologist and SSJV
MPEP Cooperating Grower; 3 UC Cooperative Extension
Contact: John Dickey, SSJV MPEP, 4886 E. Jensen Avenue, Fresno, CA 93725
916-517-2481; [email protected]
The proportion of applied nitrogen (N) used by the plant (N-use efficiency [NUE]) depends on
system operation and the design of the monitoring, irrigation, and fertigation system
components. This study is located on a 29-acre orange grove near Minkler, California, on the
Kings River fan. A similar study of an adjacent almond field provides a helpful basis for
comparison. Situated on highly permeable, moderately coarse-textured surface soils with
occasional gravel stringers. The site is underlain by a discontinuous restrictive soil layer (at 4
feet below ground surface [bgs]) and shallow groundwater (at 18-20 feet bgs). Information about
site operations, actual evapotranspiration, the water and nitrogen (N) distribution in the root
zone, and plant tissue N were used to infer the amount of nitrate moving into groundwater, and
to identify potential management changes that would improve NUE. Environmental performance
has been significantly improved by adjusting fertigation and irrigation approaches that extend N
residence time in and uptake from the root zone, even as other salts continue to move toward the
margins of the main, wetted, soil volume. Benefits of operational changes include: improved tree
growth and crop yields, decreased N movement to groundwater, and more accurate water
application.
156
6. Non-Students
WORKING WITH COMMODITY GROUPS, PROCESSORS, AND
PACKERS TO PROCURE REPRESENTATIVE CROP SAMPLES TO
ASSESS HARVEST NITROGEN CONTENT
John Dickey1, Ken Cassman1, Tim Hartz1, Daniel Geisseler2
1 South San Joaquin Valley Management Practices Evaluation Program; 2 University of
California, Davis
Contact: John Dickey, SSJV MPEP, 4886 E. Jensen Avenue, Fresno, CA 93725
916-517-2481; [email protected]
Growers and their water quality coalitions need reliable data about N removed from fields in
harvested crop materials to 1) comply with reporting requirements and 2) to plan nutrient
management programs that reasonably minimize N at risk of leaching below the root zone.
Nitrogen Concentrations in Harvested Plant Parts - A Literature Overview by Dr. Geisseler
(2016), presents yield (Y)-to-N-removed conversion factors for 72 crops, representing more than
98 percent of CV irrigated lands. However, some of these factors are based on datasets that were
small, more than 20 years old, or from outside the CV.
We are developing updated conversion factors for 25 crops. For some, information comes from
other research projects. We are sampling and analyzing harvested carrots, corn (grain and silage),
peaches, pima cotton, pistachio, plums, pomegranates, raisins, safflower, sorghum (grain and
silage), sunflower, and processing tomatoes. By partnering with commodity organizations,
growers, processors, and packers, it has been possible to procure hundreds of samples that
represent a range of varieties and growing environments for each crop. In most cases, substantial
data about source fields, such as age of perennial crops, crop management, variety, yield, quality,
and dates of bloom or planting, are acquired and related to results. In this way, some of the
factors that affect N content of the harvest can be investigated and explained. These data will be
incorporated into updates of Geisseler (2016). The existing crop Y-to-R calculator
(http://agmpep.com/calc-y2r/) will be revised to reflect these findings, and the results will be
used to update the assessment and planning tools available to growers, grower advisors, and
coalitions.
157
7. Non-Students
FIRST REPORT OF A NEW STEM AND CROWN ROT DISEASE OF
PROCESSING TOMATO IN CALIFORNIA CAUSED BY FUSARIUM
FALCIFORME
Erin Helpio, Beth Hellman, Cassandra L. Swett
University of California, Davis
Contact: Erin Helpio, UC Davis, Plant Pathology, 1 Shields Ave, Davis, CA 95616
530-752-3831; [email protected]
California produces 90% of the countries processing tomatoes, with $1,031,995 in cash receipts
for the state. In 2017, Fusarium falciforme - part of the Fusarium solani species complex
isolates (FSSC) - was recovered from processing tomatoes in three counties (13 sites) in
California exhibiting stem and crown rot symptoms. As there is no record of any species in the
FSSC causing stem and crown rot in California, we hypothesized that this was a new disease in
the state. To test this hypothesis, Koch’s postulates was conducted using three Fusarium
falciforme isolates (one from each of three counties), together with negative wound and
biological controls; pathogenicity was examined on two processing tomato cultivars, H8405 and
HM3887. Inoculations were conducted by placing spores and hyphae in a 1mm epidermal
wound at the base of the stem of 5-week-old tomato plants and internal lesions were evaluated
eight weeks later. Treatment had a significant effect on lesion length for both cultivars (P <
0.001), reflecting significantly greater lesions in the F. falciforme isolate treatments compared to
the negative controls. Average lesion length ranged from 30-50 mm with a maximum lesion
length of 105mm. There was significant variation in cultivar susceptibility in one isolate
treatment (CS 109) (P = 0.04), indicating some potential for genetic variation in tolerance. There
was no difference between wound and biological controls (lesion length range: 3-7mm). Based
on these results, Fusarium falciforme is a new stem and crown rot pathogen of processing tomato
in California. This information can be used to develop diagnostic tools and identify tolerant or
resistant cultivars for control.
158
8. Non-Students
RESPONSE OF SORGHUM AND CORN CULTIVARS TO DIFFERENT
SUB-SURFACE DRIP AND NITROGEN FERTILIZER APPLICATIONS
Bob Hutmacher, Nick Clark, Steve Wright, Jeff Dahlberg, Jorge Angeles, Rafael Solorio
California Cooperative Extension Tulare & Kings County, West Side Research and Extension
Center
Contact: Jorge Angeles, CSU Fresno, 1338 E San Ramon Ave APT H, Fresno, CA 93710
559-940-8549; [email protected]
In the San Joaquin Valley (SJV), sorghum is a crop that has the potential of producing
comparable yields to alternative forage crops with less water use. Past evaluations of studies
conducted at Kearney (KREC) and West Side (WSREC) Agricultural Research and Extension
Centers have proposed that corn cultivars have more negative impacts under severe deficit
irrigation treatments than sorghum cultivars. Additionally, limited research in California has
also suggested that forage sorghum can achieve full yields and acceptable quality with less
nitrogen (N) applications than in corn. With limited current research, it is important to identify
the yield potential and responses of sorghum to different irrigation levels and fertilizer nitrogen
applications. An irrigation study was conducted at WSREC to evaluate the responses of four
different forage sorghum cultivars and two corn cultivars to a range of different drip irrigation
amounts and fertilizer N application amounts at different maturity stages. The forage sorghum
cultivars differed in type (grain, forage), photoperiod and stature. Three sub-surface drip
irrigation treatments were used with one drip line placed in the center of every two planted crop
rows. The three irrigation treatments included a ¾ of estimated evapotranspiration needs for
forage sorghum, an estimated optimal irrigation (non-stressed) for forage sorghum, and
estimated optimal irrigation (non-stressed) for corn. The three N treatments were 100-120 lbs
N/acre, 200-220 lbs N/acre and a 0 N control treatment. This study is a follow up of prior
irrigation studies conducted under full N applications in KREC and WSREC, but with the
addition of different N and irrigation amounts to examine the interaction of deficit to full
irrigation at different N fertilizer applications.
159
9. Non-Students
BIOFUEL FEEDSTOCK PRODUCTION IN CALIFORNIA ORCHARDS
CAN INCREASE SPECIES RICHNESS AND WILL SUPPORT
POLLINATOR HEALTH
Stephen Kaffka, Nic George
University of California, Davis
Contact: Stephen Kaffka, UC Davis, Department of Plant Sciences, 1 Shields Ave.,
Davis, CA 95616
530-204-6603; [email protected]
In California’s intensive agricultural landscape like California, policies supporting alternative
fuel production provide an opportunity to increase species richness in agricultural ecosystems
and sustainably intensify land use. Land devoted to the intensive production of almonds and
other nut trees and grapevines has increased significantly in recent years in California.
Combined with drought, increased land in woody perennials has helped idle more than 400K ha
of highly productive farmland, while crop diversity has been reduced. The use of cover crops in
orchards and vineyards protects soils, may increase organic matter, and provides benefits to
pollinator health. But the costs, labor and water requirements of cover crops have limited their
use and orchards tend to be monocultures. Double cropping winter annual oilseed crops in
orchards, especially in new or replanted stands, can be achieved in many areas of the state on
winter rainfall and provides an economic return to farmers that may support the use of cover
crops when they are otherwise uneconomic. A range of commercial and novel oilseed species
including canola (B. napus), camelina (C. sativa), flax (L. usitatissimum), lupin species,
meadowfoam (L. alba) and others provides diverse opportunities for cover cropping strategies
across the state’s highly variable agroecosystems. The performance of several of these species
has been evaluated that appear suitable for use in orchards. Water use in new or replanted
orchards or in vineyards in large areas of the state with sufficient winter rainfall will not require
supplemental irrigation in most years. Canola and other mustards, and other species are
beneficial to pollinators in the absence of systemic pesticide use, unnecessary in California.
These plantings also support pollinator health and help with weed management. High yielding,
double cropped canola and camelina varieties can provide biodiesel feedstocks without the added
carbon burden associated with indirect land use changes, while the state’s low carbon fuel
standard (a performance-based regulation) provides strong economic incentives to support the
production of double cropped oilseeds. In turn, the low carbon intensity of these feed stocks
increases their economic value compared to more traditionally produced oilseed crops.
160
10. Non-Students
YIELD PROGRESS AND RESOURCE USE IN SUGARBEET
PRODUCTION IN THE IMPERIAL VALLEY OF CALIFORNIA
Stephen Kaffka, Ron Tharp
University of California, Davis
Contact: Stephen Kaffka, UC Davis, Department of Plant Sciences, 1 Shields Ave.,
Davis, CA 95616
530-204-6603; [email protected]
The Imperial Valley (IV) is a low desert ecosystem with mild, sunny winters and hot summers.
It receives the largest amount of sunlight of any location in the United States. Most soils are
high in pH and calcareous, with large amounts of naturally occurring gypsum. The majority of
fields are tile drained at 2m in depth. Subsurface drainage maintains positive salt balances in the
IV soils. Season-long irrigation is necessary for the beet production season from September to
mid-July. Crop ETc is approximately 1200 to 1500 mm for a 10 month crop. Beet harvest
starts at approximately 180 days in early April and continues to mid-July (260 days). Starting in
the 1990s, root yields rose at the rate of ~ 1.9 t/ha/y, and sugar yields by approximately 0.4
t/ha/y, while sugar concentration has varied around a stable mean, which declines with each
month of harvest, as does root quality. Monthly dry matter accumulation during the April to
June period has increased significantly during this period compared to earlier periods. Yield
increases are attributed to a variety of interacting factors: 1. improved performance of new
hybrids, including improved rhizomania resistance; 2. reduction in losses to lettuce infectious
yellows virus starting in the early 1990’s; 3. better control of weeds; 4. the adoption of newer
style harvesters allowing for harvest from moister soil, (also permitting irrigation closer to
harvest); 5. better management and timing of late season irrigations during the hottest weather;
6. improved seed quality and stand establishment practices; and 6. a partial shift to production
on better quality soils in recent years. Individual field-scale root and gross sugar yield records
continue to be observed for full season beet crops (9 to 10 months). Averages for the 8 largest
contracts during 2015 and 2016 crop years were: (2015) 173 t/ha roots and 25.6 t/ha sugar, and
(2016) 160.7 t/ha roots, 24.0 t/ha sugar. The largest yield observed at a field scale (30 ha) to date
was 199.2 t/ha roots and 27.2 t/ha sugar in 2015. These high yields are similar to those observed
from the leading sugar beet varieties in tests in the IV so the difference between potential and
actual yield in the IV is declining. These high yields are similar to those observed from the
leading sugar beet varieties in tests in the IV, so the difference between potential and actual yield
in the IV is declining. New irrigation monitoring and application techniques and improved
fertilizer recommendations suggest increases in resource use efficiency can also be achieved at
these yield levels.
161
11. Non-Students
CAN BIOCHAR CONSERVE WATER IN AGRICULTURAL SOILS?
Sarah E. Light1, Claire L. Phillips2, Hero Gollany3, Thomas Waznek2, Kristin M. Trippe2
1 University of California Cooperative Extension, Yuba City, CA; 2 USDA-ARS Forage Seed
and Cereal Research Unit, 3450 SW Campus Way, Corvallis, OR 97331; 3 USDA-ARS
Columbia Plateau Conservation Research Center, 48037 Tubbs Ranch Road, Adams, OR 97810
Contact: Sarah Light, UCCE Yuba County, 142 A Garden Highway, Yuba City, CA 95991
530-645-2419; [email protected]
Soil management practices that increase water holding capacity and retention can help make
agricultural lands more resistant to drought. While laboratory studies have demonstrated that
biochar can improve these edaphic factors, field scale studies remain limited. To evaluate the
relevance of biochar for agricultural production, gasified wheat straw (WS) and conifer wood
(CW) biochars were tilled into replicated field plots at rates of 1.7, 3.6, and 7.1 Mg ha-
1 (equivalent to 0.5, 1, and 2% by mass in the top 12 cm) at four agricultural research stations
across Oregon. Treatments were implemented in replicated field plots in fall 2016, and sampled
the following spring for water infiltration, water retention, and soil physical characteristics.
Treatments were evaluated in diverse soil textures including a loam, silt loam, sandy loam, and
loamy sand. Infiltration rates were highly variable. Total porosity and saturated water content
increased with higher biochar amendment rates, and most soil-biochar combinations also
increased plant-available water content. However, it seems that water retention with biochar
treatments shifted from micro- to meso- and macro-pores, and that most of the increase in pore
space was associated with porosity between biochar and soil particles, rather than with pores
internal to biochar particles. Additionally, in situ measurements at one site showed that
evaporation rates after irrigation were higher with biochar amendment. It appears that this
creation of larger pores, from which water can readily evaporate, was responsible for the
increases in plant-available water and total water holding capacity. The stability of these pores,
and thus long-term impact on soil water dynamics, is unknown.
162
12. Non-Students
MONITORING OF BROWN MARMORATED STINK BUG (BMSB) IN
ALMOND AND PEACH ORCHARDS IN THE NORTHERN SAN
JOAQUIN VALLEY
Adriana Medina, Tania Herrera, and Jhalendra Rijal
University of California Cooperative Extension
Contact: Jhalendra Rijal, UCCE Stanislaus County, 3800 Cornucopia Way, Ste. A,
Modesto, CA 95358
209-525-6800; [email protected]
Brown marmorated stink bug (Halyomorpha halys) (BMSB) is an invasive insect species from
Asia first detected in Pennsylvania in the late 1990s and currently spread to over 43 states
including California. Since the finding of a large population in Sacramento in 2013, BMSB has
been spread and established in 16 California counties from Butte to Fresno. Both adults and
nymphs (2nd-5th instars) actively feed on the fruiting structure of the host plants that includes
more than 170 species of ornamental and landscape trees, field, vegetable, and tree crops. They
insert the ‘straw-like’ mouthpart into the fruit and seed, release salivary enzymes and uptake the
dissolved content. In general, feeding results in surface gumming, deformations to internal
necrosis on fruits while causing significant damage to nutmeat in almonds. We reported the
established BMSB population in commercial orchards (peach in 2016; almond in 2017) in the
northern San Joaquin Valley as the first report of crop infestation by BMSB in California. In
2017 and 2018, we conducted monitoring of BMSB in several peach and almond orchards using
two types of traps (black pyramid, and sticky panel), baited with BMSB lures. Both BMSB
adults and nymphs were captured in several peach and almond orchards in both years indicating
the spread of BMSB to a wider area than previously known. Field collected fruits were evaluated
at different times of the year to assess the overall damage by stink bugs to the fruits and nuts.
The results will be discussed in relation to the seasonal phenology of this pest in the upper San
Joaquin Valley, and the potential risks to the fruit and nut crops grown in the area.
163
13. Non-Students
ROTATION CROPS AS HIDDEN HOSTS OF THE FUSARIUM WILT
PATHOGEN OF TOMATO, FUSARIUM OXYSPORUM F. SP.
LYCOPERSICI
Rino Oguchi and Cassandra Swett
University of California, Davis
Contact: Rino Oguchi, UC Davis, Plant Pathology, 1 Shields Ave, Davis, CA 95616
530-752-3831; [email protected]
Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici Race 3 (Fol R3) is a
widespread disease across California, causing up to 100% yield loss. Crop rotation is frequently
used to reduce the pest population in soil; however, after several years of rotation, fields
replanted to susceptible tomato still suffer Fusarium wilt losses. We hypothesized that some
rotation crops are symptomless hosts, allowing the Fol R3 population to persist in soil. In
greenhouse trials, we evaluated the host status of warm and cool season crops commonly rotated
with tomato in California. Of the warm season crops, corn, pepper, rice, cotton, sunflower, lima
bean, melon and pumpkin were systemically colonized by Fol R3. The extent of stem
colonization in cotton (Malvaceae), pumpkin and melon (Cucurbitaceae) was not different from
tomato (P > 0.05). Stem colonization in lima bean (Fabacaea), pepper (Solanacaea), sunflower
(Asteracaea), corn and rice (Poaceae) was significantly lower than tomato (P< 0.05). Patterns
were similar based on the highest point of stem infection, with the exception that colonization in
sunflower and melon was intermediate between tomato (highest) and rice (lowest). Of the cool
season crops, onion, wheat and arugula were systemically colonized by Fol R3 but the extent of
stem colonization was 80% lower than tomato on average; further analyses are underway. These
treatments reveal that many crops can be cryptic hosts to Fol R3, and that Malvaceae and
Cucurbitaceae crops should especially be avoided in rotation while certain grass crops may help
manage soil inoculum loads, particularly in the first year out of tomato.
164
14. Non-Students
THE EFFECT OF DEFICIT IRRIGATION ON DEVELOPMENT OF
FUSARIUM WILT IN TOMATO
Kelley R. Paugh, Cassandra L. Swett
University of California, Davis
Contact: Kelley R. Paugh, UC Davis, Plant Pathology, 1 Shields Ave, Davis, CA 95616
530-752-3831; [email protected]
Fusarium wilt of tomato, caused by Fusarium oxysporum f. sp. lycopersici (Fol) race 3, is a
soilborne disease that causes serious yield losses in California processing tomatoes. Tolerant
cultivars provide a semi-effective management solution, but tolerance appears to break down
over a certain threshold inoculum load and may also be compromised by stress. Decreasing
surface water availability has driven the use of deficit irrigation methods that utilize water more
efficiently. However, this irrigation practice may shift Fusarium wilt risk threshold levels and
increase losses in tolerant cultivars. We evaluated the effect of deficit irrigation on disease
development in a tolerant tomato cultivar (HM 3887) under variable inoculum loads (0, 102, 104,
or 106 spores/mL) of Fol race 3, comparing full irrigation (45% volumetric water content
(VWC)) to moderate deficit (35% VWC) and severe deficit (28% VWC). The effect of
inoculum load was significant at 45, 35, and 28% VWC. After treatment with 104 spores/mL,
disease incidence was four-fold higher under severe deficit (28% VWC) than higher moisture
levels — but this difference was not significant. Although deficit irrigation was associated with
lower plant growth and yield, effects on disease were not significant. Analyses of irrigation
treatment effects on infection and soil inoculum load are underway. Based on these results, more
severe water deficits could potentially predispose plants to Fusarium wilt, whereas mild water
deficits do not appear to increase disease risk.
165
15. Non-Students
GREENHOUSE GAS (N2O AND CO2) EMISSIONS FROM HIGH RATE OF
WOODCHIP RECYCLING IN AN ALMOND ORCHARD
Julio Perez1, Diana Camarena1, Robert Shenk, Aileen Hendratna, Tom Pflaum, Mae Culumber,
Amisha Poret-Peterson, Brent Holtz, and Suduan Gao1
1 USDA-ARS, San Joaquin Valley Agricultural Sciences Center
Contact: Suduan Gao, USDA-ARS, 9611 S. Riverbend Ave., Parlier, CA 93648
559-596-2870; [email protected]
Whole orchard recycling (WOR) provides several potential benefits in orchards to increase soil
organic matter/carbon and nutrients, improve soil physical properties, and promote microbial
diversity for ultimate better soil health and productivity. However, there are many knowledge
gaps on the impact of WOR on soil carbon and nutrient dynamics including greenhouse gas
emissions. The aim of this research was to collect field data and evaluate the effects of one time
high rate of recycled woodchip application on nitrous oxide (N2O) and carbon dioxide (CO2)
emissions. An old plum orchard was pulled out, chipped, incorporated into surface soil, and new
almond trees were planted in late 2017. Emission rates of N2O and CO2 using static chambers
were measured in control plots (no woodchip) and woodchip incorporated plots since early 2018.
Nitrogen fertilizers were applied six times (approximately every month) from April through
August. Nitrous oxide emissions peaked following each fertilizer application, but dropped
quickly in a few days. Woodchip incorporated plots had much higher N2O emission peaks
following each fertilization than the control, but little difference was observed after 1-2 weeks.
The data suggest that N fertilizer was the key factor in affecting N2O emissions. Carbon dioxide
emissions were consistently higher in woodchip plots than the control and much higher from
April through June compared to the period of July through September, indicating higher
microbial activities or more available C for mineralization from woodchip plots. This research
continues to observe long-term effects of woodchip incorporation on soil C and N dynamics in
the orchard to provide useful information on management strategies.
166
16. Non-Students
QUANTIFYING NITRATE LEACHING FROM CENTRAL VALLEY
IRRIGATED LANDS WITH THE SOIL & WATER ASSESSMENT TOOL
(SWAT)
Yohannes Yimam, George Paul, Tim Hartz, John Dickey, and Ken Cassman
South San Joaquin Valley Management Practices Evaluation Program
Contact: John Dickey, SSJV MPEP, 4886 E. Jensen Avenue, Fresno, CA 93725
916-517-2481; [email protected]
Central Valley Growers regulated under the Irrigated Lands Regulatory Program (ILRP) are
required to assess the effects of crop management practices on groundwater quality. Such
assessments are complex when performed on a single, relatively uniform experimental plot.
Methods used for such small areas cannot be readily adapted to evaluate the Central Valley’s
approximately 6.2 million acres of irrigated lands. Fortunately, agencies like EPA and NRCS
developed computer-based tools such as the Soil and Water Assessment Tools (SWAT), and an
ArcGIS-enabled version (ArcSWAT), which operate at field and soil mapping unit scales,
combining results for whole watersheds or regions. These tools join physically and biologically
based models of crop growth, hydrologic, and soil processes that contain user-defined
management parameters. In addition to allowing users to assess a broad range of field conditions,
SWAT accommodates readily available, digital climatic, soil, land cover, topographic, and
hydrologic databases, so these need not be developed from scratch. SWAT’s physical basis
allows it to run without depending on empirical relationships derived from monitoring; therefore,
areas and parameters where measurements are lacking can be assessed. SWAT applications have
been documented extensively in over 3,500 peer-reviewed papers, including sensitivity analysis,
calibration, validation, and specific applications at a variety of scales, geographies, in various
cropping and management systems, and for various water quality constituents. ILRP coalitions
use SWAT as a first step in the required assessment. Underlying databases and inputs that
represent Central Valley conditions and cropping systems were developed and are being applied
to the full extent of irrigated lands in the region. Methods will be explained, and initial results for
the Southern San Joaquin portion of the domain will be presented.
167
NOTES
168
NOTES
169
Chapter web site: http://calasa.ucdavis.edu
California Chapter – American Society of Agronomy
2019 Plant and Soil Conference Evaluation
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