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Antagonism of ACCase Inhibitor Herbicides Used in Xtend Soybean

Systems for Control ofVolunteer Corn

Marcelo Zimmer, Bryan G. Young,

and William G. Johnson

• Weed that grows from corn grain left in the fields after harvest

• Impact: Soybean yield losses, corn rootworm host, and harvest issues 1, 6

• Herbicide options vary according to corn herbicide-tolerance traits planted

• High efficacy of aryloxyphenoxypropionate (FOPs) and cyclohexanedione (DIMs) graminicide families reported on volunteer glyphosate-resistant corn 1, 5, 7, 9

Volunteer Corn

Volunteer corn sprouting from corn ears.Photo: Amit Jhala

Volunteer corn clumps.Photo: Jenny Rees

Antagonism of ACCase Herbicides

• Synthetic auxin herbicides and glyphosate

are known to antagonize ACCase inhibitor

herbicides on volunteer corn 3, 4, 8, 10, 11, 12

• Widespread adoption of Xtend soybeans

for management of herbicide-resistant

weeds

• Industry research reports show reduced

volunteer corn control with clethodim

when tank-mixed with dicamba and/or

acetochlor 2

Necrosis of growing point at whorl following application of ACCase inhibitor herbicides

Plants stop growing within hours of application and newer leaves die first

• Hypothesis: The addition of dicamba plus glyphosate and/or acetochlor will reduce the efficacy of clethodim and quizalofop on volunteer corn. The antagonistic effect of dicamba plus glyphosate and acetochlor these herbicides can be overcome by increasing ACCase field use rates by 50%.

• Objectives:

Investigate the effect of dicamba and acetochlor on the efficacy of two ACCase herbicides (clethodim and quizalofop) used for volunteer corn control

Evaluate the effect of ACCase inhibitor field rates used in tank-mixtures with dicamba and/or acetochlor

Hypothesis and Objectives

• Field experiment conducted during 2020

RCBD with 4 replications

• Three corn hybrids planted at 90,000 seeds ha-1 across Xtend (Asgrow AG29X9) soybean plots (3 x 9 m):

Non-GMO

Federal Hybrids RK112

SmartStax®

Dekalb DKC62-52RIB

Enlist® + SmartStax®

Mycogen MY10Z29

Materials and Methods

Non-GMO RR2/LL Enlist

• Field experiment conducted during 2020

RCBD with 4 replications

• Three corn hybrids (F1) planted at 90,000 seeds ha-1

across Xtend (Asgrow AG29X9) soybean plots (3 x 9 m):

Non-GMO

Federal Hybrids RK112

SmartStax®

Dekalb DKC62-52RIB

Enlist® + SmartStax®

Mycogen MY10Z29

Materials and Methods

Non-GMO RR2/LL Enlist

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• Factorial arrangement of herbicide treatments plus nontreated control: Factor 1 – ACCase herbicide: quizalofop or

clethodim

Factor 2 – ACCase rate: clethodim @ 70 or 105 g ai ha-1 (low and high rate)

quizalofop @ 31 or 46.3 g ai ha-1 (low and high rate)

Factor 3 – Addition of dicamba (560 g ae ha-1) plus glyphosate (1260 g ae ha-1)

Factor 4 – Addition of acetochlor (1260 g ai ha-1)

Herbicide Treatments Herbicide Treatments

• Ammonium sulfate (AMS) and crop oil concentrate (COC) added to all treatments without dicamba + glyphosate

• Drift reducing agent (DRA) and non-ionic surfactant (NIS) added to all treatments with dicamba + glyphosate

• All treatments sprayed with Teejet TTI110015 nozzles at 140 L ha-1

• Volunteer corn height at application: 20 to 48 cm (V5 to V6)

• Visual control (0 to 100% scale) at 7, 14, and 21 days after treatment (DAT)

• Corn density (plants m-2) and number of corn ears (corn ears m-2) at soybean harvest

• Factorial Analysis of Variance using PROC GLIMMIX in SAS 9.4 and mean separation with Tukey’s HSD test

Data Collection and Analysis Results and Discussion

Factorial ANOVA – RR2/LL Control 21 DAT

Type III Tests of Fixed EffectsEffects Pr > FACCase herbicide (ACC-H) <0.001

ACCase rate (ACC-R) <0.001

ACC-H * ACC-R <0.001

Dicamba + glyphosate (DicGly) <0.001

ACC-H * DicGly <0.001

ACC-R * DicGly <0.001

ACC-H* ACC-R * DicGly 0.001

Acetochlor (Aceto) 0.007

ACC-H * Aceto <0.001

ACC-R * Aceto 0.195

ACC-H * ACC-R * Aceto <0.001

DicGly * Aceto 0.003

ACC-H * DicGly * Aceto <0.001

ACC-R * DicGly * Aceto 0.158

ACC-H * ACC-R * DicGly * Aceto 0.003

• Four-way interaction with p-value = 0.003

RR2/LL Control @ 21 DAT - Clethodim

b aa aa bc a

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RR2/LL Control @ 21 DAT - Clethodim

clet (low) + dic + gly

clet (high) + dic + gly

clet (low) + dic + gly + acet

clet (high) + dic + gly + acet

RR2/LL Control @ 21 DAT - Quizalofop

c abab aab abc b

RR2/LL Control @ 21 DAT - Quizalofop

quiz (low) + dic + gly

quiz (high) + dic + gly

quiz (low) + dic + gly + acet

quiz (high) + dic + gly + acet

RR2/LL Density @ Harvest

ab

de

e

ab

a

de

bc

de

cd

Conclusions

• The addition of dicamba plus glyphosate to POST applications of clethodim or quizalofop reduces control of volunteer corn in Xtend soybean systems

• Acetochlor reduces clethodim efficacy when tank-mixed with dicamba plus glyphosate

• The addition of acetochlor does not appear to reduce volunteer corn control with quizalofop

• Increasing the rate of ACCase herbicides by 50% resulted in increased efficacy, although many treatments resulted in standing plants at soybean harvest

• ACCase rates higher than the rates tested in this experiment are necessary to overcome herbicide antagonism when tank-mixing ACCases with dicamba plus glyphosate, especially if acetochloris added (clethodim only)

• Split POST applications and improved adjuvant use could be other alternatives for overcoming the antagonism of ACCase-inhibiting herbicides with dicamba

Implications

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• Investigate the physiologic basis for the antagonistic response of clethodim to the addition of acetochlor plus dicamba

• Assess the efficacy of ACCase inhibitor herbicides tank-mixed with dicamba and other group #15 residual herbicides (s-metolachlor and pyroxasulfone)

• Evaluate the effect of broadleaf herbicides labeled for use on Enlist E3 soybean systems (2,4-D, glyphosate, glufosinate) in tank-mixtures with ACCase-inhibiting herbicides on volunteer corn control

Future Research Acknowledgements

• Purdue weed science lab

References

1. Alms J, Moechnig M, Vos D, Clay SA (2016) Yield loss and management of volunteer corn in soybean. Weed Technol 30:254–262

2. Anonymous (2019) Investigating potential antagonism of Select Max® herbicide when mixed with Warrant® herbicide and dicamba. Bayer 2018 Research Report. https://www.corn-states.com/app/uploads/2019/02/Investigating-Potential-Antagonism-of-Select-Max%C2%AE-Herbicide-When-Mixed-with-Warrant%C2%AE-Herbicide-and-Dicamba_Bayer.pdf Accessed: November 13, 2020

3. Barnwell P, Cobb AH (1993) An investigation of aryloxyphenoxypropionate antagonism of auxin-type herbicide action on proton-efflux. Pestic Biochem Phys 47:87–97

4. Barnwell P, Cobb AH (1994) Graminicide antagonism by broadleaf weed herbicides. Pestic Sci 44:77–85

5. Chahal PS, Jhala AJ (2015a) Herbicide programs for control of glyphosate-resistant volunteer corn in glufosinate-resistant soybean. Weed Technol 29:431–443

6. Chahal PS, Jhala AJ (2015b) Impact of glyphosate-resistant volunteer corn (Zea mays L.) density, control timing, and late-season emergence on yield of glyphosate-resistant soybean (Glycine max L.). Crop Prot 81:38–42

7. Deen, W, Hamill A, Shropshire C, Soltani N, Sikkema PH (2006) Control of volunteer glyphosate-resistant corn (Zea mays) in glyphosate-resistant soybean (Glycine max). Weed Technol 20:261–266

8. Harre NT, Young JM, Young BG (2020) Influence of 2,4-D, dicamba, and glyphosate on clethodim efficacy of volunteer glyphosate-resistant corn. Weed Technol. 34:394–401. doi: 10.1017/wet.2019.124

9. Kniss AR, Sbatella GM, Wilson RG (2012) Volunteer glyphosate-resistant corn interference and control in glyphosate-resistant sugarbeet. Weed Technol 26:348–355

10. Mueller TC, Witt WW, Barrett M (1989) Antagonism of johnsongrass (Sorghum halepense) control with fenoxaprop, haloxyfop, and sethoxydim by 2,4-D. Weed Technol 3:86–89

11. Underwood MG, Soltani N, Hooker DC, Robinson DE (2016) The addition of dicamba to POST applications of quizalofop-p-ethyl or clethodim antagonizes volunteer glyphosate-resistant corn control in dicamba-resistant soybean. Weed Technol 30:639–647

12. Young BG, Hart SE, Wax LM (1996) Interactions of sethoxydim and corn (Zea mays) postemergence broadleaf herbicides on three annual grasses. Weed Technol 10:914–922

Questions?

Photo: Travis Legleiter

Marcelo Zimmerzimmer6@purdue.edu Office: (765) 496-2121

@MarceloZimmer3

Dr. Bill Johnsonwgj@purdue.edu

Office:(765) 494-4656@BillJohnson53