Jim HeiserUniversity of Missouri-Fisher Delta Research
Center Weed Science Project
Fisher Delta Research Center CCA Days
Everything you didn’t realize you wanted to know about rice weed
control
Outline
• Herbicide Resistance• In rice• Rotational crops
• Product Update• Drift Issues• Rice Weed Control Basics
Resistance Issues in Rice
Weed Mode of Action Group Typical Example Location
Smallflower Umbrella Sedge ALS Londax, Permit California, Arkansas, Missouri?
Rice Flatsedge ALS Regiment, Grasp, NewPath, Permit Arkansas
Red Rice ALS Imazethapr, Imazapic Brazil
California ArrowheadALS Londax, Grasp, Imazethapyr California, Brazil
Nitriles and Others Basagran Brazil
Barnyardgrass
ALSRegiment, Imazethapyr
GraspBrazil, Arkansas, Mississippi
Thiocarbamates Ordram, Bolero California
ACCase Clincher, Ricestar HT California, Mississippi
Ureas/Amides Propanil Arkansas, Mississippi
Synthetic Auxins Facet Mississippi, Arkansas, Brazil
Triazoles, Ureas, Isoxazolidiones Command Arkansas
Amazon Sprangletop ACCase Clincher, Ricestar HT Louisiana
Yellow Nutsedge ALS Permit Arkansas
Smallflower Umbrella Sedge
Charles T Bryson
VS.
YellowTubers on roots
(purple=tubers on
rhizomes in chains)
Gradually tapering leaves
Few viable seeds
D. Dodds
SmallflowerDoes NOT have tubers
Sharply pointed leaves
Annual propagated by
seeds
Smallflower Umbrella Sedge
Charles T Bryson
VS.
SmallflowerLondax (1993)
Permit (2009)
Grasp (2005?)
YellowDifficult to control in many
situations
BUT…
Not herbicide resistant!?
D. Dodds
• ALS resistance
• Viable seed?
• 1 oz Permit replaced by
• 1 gallon Propanil
• + 1.5 qt Bolero
• fb 1.5 pt Basagran + oil
Yellow Nutsedge
Rice Flatsedge
Similar in size to Smallflower Umbrella Sedge
Smaller than yellow nutsedge
“Christmas Tree” smell
No tubers or rhizomes
Reproduction by seeds
Rice Flatsedge
• 4 to 6 weeks from seed to seed• Dense populations• Short days
• Usually easy to control• Small colonies of susceptible plants
• Resistant populations tend to be• Dense population=very competitive• Cross resistant to other ALS• Propanil + Basagran
California Arrowhead
Andy Kendig
• Rectangular markings on leaves distinguish it from ducksalad
• Like most aquatics, best control is healthy dense rice stand.
• Basagran, Propanil still work
• Generally identical
• Undesirable characteristics
• ALS resistance
• Clearfield
• Natural
• Could be worse
• Rotation!
Red Rice
Amazon Sprangletop
Pam Trewatha Jim Stritzke
• Several similar species
• Long, narrow panicle
• Bearded has long, membranous ligule
• Ligule similar to red sprangletop• No hairy sheath
Amazon Sprangletop
• Resistant to Clincher and Ricestar• Resistant to other “Grass” herbicides?• Does it matter?
Junglerice
Tomas Marquez/DuPont-Spain
• Similar to barnyardgrass• Slightly prostrate
• Rooting nodes
• Smooth leaves• Awnless, slightly
larger seeds
• Purple band on leaves
Junglerice
• Populations resistant to 3 MOA’s• Propanil, Ricestar and ALS
• Another population resistant to Facet
• Resistant to 8 modes of action world-wide!• Rice herbicide families
• Triazines• Atrazine
• Chloroacetamides• Butachlor and pretilachlor
Barnyardgrass
• Syn. Auxins
• Thiocarbamates
• Triazolinones
• Ureas/Amides
• ALS inhibitors
• Dinitroanilanes
Barnyardgrass
Not all Barnyardgrass is resistant to all six MOA’s listed, but…• Multiple MOA resistance documented
• Propanil + Facet• Propanil + Facet + NewPath• Propanil + Facet + Command
• Propanil + Facet + NewPath + Command + Clincher + Prowl?
Bad Scenario
• What if we lose a MOA useful in another crop?• Soybean
• Lipid Synthesis Inhibitors (ACCase)• Red Rice, Barnyardgrass• Select, Poast and Clincher, Ricestar
• Branched Chain Amino Acid Inhibitors (ALS)• Already have in some cases• Pursuit, Classic, Scepter and NewPath, Grasp,
Permit
Bad Scenario
What if we lose a MOA useful in another crop?
• Soybeans, Corn, Cotton• Inhibitors of Cell Division (Chloroacetamides)
• Rice elsewhere• Dual, Warrant, and Butachlor, Pretilachlor
• Corn• Inhibition of pigment synthesis (4-HPPD)
• Callisto, Balance Flexx, Laudis and Benzobicyclon
• Herbicides do not create resistant plants
• Naturally present
• Selection
• Lack of competition
• Cross resistance
• Multiple resistance
Resistance Detection
• Early detection
• Limits spread
• Control measures
• Failures ≠ Resistance
Resistance Detection
• Improper rate• Improper application• Poor timing/size• Degree of infestation
• Weather• Secondary flush• Antagonism
Indicators include
• Good performance + Poor performance
• Ideal conditions = poor control
• Localized in field
• Intra-species control
• Field history
• Gradual decrease
Resistance Detection
Resistance Summary
“Path of Least Resistance”
• Don’t overuse one option• Alternatives inferior
• Overlap residuals • Different modes of action
• Rotate crops• Goal = 100% control • Best fit for each crop
Outline
• Herbicide Resistance• In rice• Rotational crops
• Product Update• Drift Issues• Rice Weed Control Basics
Disclaimer
Use of products and trade names does not
constitute a guarantee or warranty of the products
named and does not signify that these products are
approved to the exclusion of comparable products.
Use of trade names does not imply an endorsement
by the University of Missouri or by an employee of
the University of Missouri.
Product Update
• Obey• Clomazone + Quinclorac
• Strada Pro• Orthosulfuron + Halosulfuron
• Strada XT2
• Orthosulfuron + Quinclorac
Benzobicyclon
• GWN-10235
• New a.i. and m.o.a.
• Grass, broadleaf and sedge activity
• Water depth dependent
Lasting Results
Treated in 2012
Treated in 2012
Untreated in 2012
Untreated in 2012
Outline
• Herbicide Resistance• In rice• Rotational crops
• Product Update• Drift Issues• Rice Weed Control Basics
Movement of spray particles from intended target to other areas
• Physical • Any chemical • wind, temperature, pressure
• Vapor• Product formulation • Air temperature• Difference in air/soil temp• Less obvious
Eric Webster, LSU
Herbicide Drift on Rice
What is Herbicide Drift?
Misconceptions
• Spray early and spray late
• Low wind = less drift
• NO wind = less mixing of air
• Inversions
• Very low winds tend to be unpredictable
• Difficult to adjust swath in swirling winds
Steady 3-10 mph windsprovide good mixing of air and reduce inversions
How to Avoid Drift
• Short answer – You can’t! (completely)
• You can reduce drift by
• Lowering sprayer pressure
• Increase carrier volume
• Using the correct tips
• Make sure the nozzle is also recommended for the type of application and the chemical you are using.
How to Avoid Drift
• Boom design and placement• Wide pattern tips • Closely spaced nozzles• 20 inches
• Drift Control Agents• Thickens• Increases droplet size
• Vapor Drift • Amine vs. Low Volatility Esters • Environment
Herbicide Drift on Rice
• Glyphosate
• NewPath and Beyond
• GlufosinateEric Webster, LSU
Eric Webster, LSU
Glyphosate Drift on Rice
Missouri Rice Surrounded by Glyphosate Resistant Crops
• Early season drift symptoms include
• Total plant death
• Roots dying
• Drought stressed
• Yellowing
• Leaf rolling
Dr. Nathan Buehring, MSU
Glyphosate Drift on Rice
• Reproductive phases• 50% yield reduction• Small black necrotic area around developing
seedhead (14 DAT)
• May not be noticeable until harvest• Blank heads• Deformed heads• Beak shaped seeds• Straighthead appearance
• shortened flag leaf
NewPath Drift on Conventional Rice
Early Season Drift Symptoms Include
• Yellow and/or purple tinted leaves
• Newest leaf
• onion rolled
• dead
Dr. Nathan Buehring, MSU
NewPath Drift on Conventional Rice
• Drift at later stages of development can cause
• Heads fail to emerge
• Heads rot inside plant
• Stunted seed heads
• Beyond drift will be similar
Less destructive than
glyphosate after PI stage
• Reproductive or Vegetative
• Cosmetic unless severe
• Yellowing
• Speckling
• Lesions
• New leaves OK
Glufosinate Drift on Rice
LSU AgCenter
LSU AgCenter
• Where is injury• Irregular
• Uniform
• One side
• Symptoms• Dead
• Internode length
• Other vegetation• Roadsides, ditches, levees, treelines
Drift Detection
LSU AgCenter
Outline
• Herbicide Resistance• In rice• Rotational crops
• Product Update• Drift Issues• Rice Weed Control Basics
RICE WEEDS
• Similar to other crops
• Barnyardgrass
• Hemp sesbania
• Morningglory
• Unique weeds
• Sprangletop
• Aquatics
TOUGHEST RICE WEED
• Red rice
• Identical genus & species
• Identical herbicide response/biochemistry
• Herbicide tolerant rice
• Clearfield, Liberty Link, Roundup Ready
• Red rice and “commercial” rice are sexually compatible and can cross breed
TOUGHEST RICE WEED
• Red rice• Identical genus & species
• Identical herbicide response/biochemistry
• Herbicide tolerant rice
• Clearfield, Liberty Link, Roundup Ready, ACCase
• Red rice and “commercial” rice are sexually compatible and CAN CROSS BREED
Why Flood
• Non-flooded possible
• Weed Control• More intensive
• Expensive
• Fertility• Limits volatilization
• Water, soil and price
Gene Stevens
• Drill seeded• Intense weed control for short period
• Easy Fertility
• Flushing
• Timely Flood = #1 Weed Problem
• Water Seeded• Always flooded
• Pegging
• Aquatics
Two Basic Systems
Water IS an Herbicide!
• Flood effectively controls weeds
• ~ 85% drill seeded
• ~95% water seeded
• Stops germination, rarely growth
• Broadleaves and Aquatics
• Competition/weak stand
• Worse in waterseeded
Fisher Delta Research Center Staff
University of Missouri Extension
Drift informationDr. Eric Webster
Dr. Justin HensleyBruce Schultz
Acknowledgements
Contact Information
Jim Heiser
Fisher Delta Research Center
PO Box 160
147 State Hwy T
Portageville, MO 63873
(573) 379-5431 (O)
(573) 999-3748 (C)
www.plantsci.missouri.edu/deltaweeds