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