Evaluation of Acuron as a new Herbicide for Weed Control in Corn G.B. Montgomery*, L.E. Steckel, and J.C. Holloway, Jr.

Herbicide Resistant Weeds Herbicide resistant weeds are becoming increasingly common and problematic in all major agronomic crops (Heap 2014) Diversifying weed management tactics is essential to mitigating this problem Increasing herbicide modes of action is one effective strategy (Owen et al. 2014)

Glyphosate-resistant Weeds

Acuron Under development from 2008-2014 by Syngenta Anticipated release for 2015 growing season Contains 4 active ingredients with 3 modes of action Bicyclopyrone Mesotrione S-metochlor Atrazine

Acuron Under development from 2008-2014 by Syngenta Anticipated release for 2015 growing season Contains 4 active ingredients with 3 modes of action Bicyclopyrone Mesotrione S-metochlor Atrazine

Bicyclopyrone Mode of action: HPPD Inhibitor Soil and foliar weed control activity Burndown, PRE, and POST emergence activity Performance under multiple tillage systems Complementary control spectrum to mesotrione Only available as a premix component of Acuron

Acuron Formulation: 3.44 lb/gal ZC Rate Structures: 1.25 – 1.5 qt/A in program with mesotrione POST 2.5 – 3.0 qt/A in program w/o mesotrione POST Active Ingredient Low Rate (lb ai/A) High Rate (lb ai/A) WSSA Group No. Bicyclopyrone 0.0185-0.022 0.037-0.044 27 Mesotrione 0.075-0.089 0.150-0.178 S-Metolachlor 0.6685-0.7975 0.1337-1.595 15 Atrazine 0.3125-0.375 0.625-0.750 5

Acuron Crops Application in field corn: Alone or in tank mixture PRE and POST use in field corn, silage corn, and seed corn PRE only use in sweet corn and yellow popcorn Application in field corn: 28 days prior to planting through 12” corn Alone or in tank mixture Atrazine Paraquat Glyphosate

Justification Acuron is a new herbicide that could soon be available for producers. Research was conducted to increase knowledge base around the new herbicide and active ingredient.

Objective Compare the efficacy of Acuron to other currently available herbicide premixes.

Materials and Methods Locations: Jackson, TN Milan, TN Experimental Design: Randomized Complete Block Application: CO2 Backpack Sprayer; 15 GPA Analysis: Proc Mixed, SAS 9.3; α = 0.05

Materials and Methods Data Collected: Application Timing: Injury: 7 DA-A - mid-season Weed Control: 7 DA-A - mid-season Application Timing: Jackson (PRE Study): Applied immediately after planting Milan (Program Study): Application A: immediately after planting Application B: applied 42 d after planting

Materials and Methods Jackson Milan Variety N-74R RR/LL Pioneer 1412HR Planted 4/1/2014 4/8/2013 Population (seed/A) 30,000 Row Spacing (inches) 30 Weed Species Annual grasses Amaranthus palmeri Ipomoea lacunosa Amarathus hybridus Abutilon theophrasti

Treatments – Jackson PRE Herbicide Active Ingredient lb ai/A Acuron bicyclopyrone, mesotrione, S-metolachlor, atrazine 0.037, 0.150, 1.337, 0.625 Acuron + Atrazine + atrazine 0.75 Anthem ATZ atrazine + pyroxasulfone + fluthiacet-methyl 1.00, 0.121, 0.004 Corvus thiencarbazone-methyl + isoxaflutole 0.033, 0.082 SureStart acetochlor, clopyralid, flumetsulam 0.938, 0.095, 0.030 Verdict saflufenacil, dimethenamid-P 0.045, 0.391

Treatments - Milan PRE Herbicide Active Ingredient lb ai/A POST Herbicide Acuron (Low) bicyclopyrone, mesotrione, S-metolachlor, atrazine 0.019 0.075 0.669 0.313 Halex GT S-metolachlor, glyphosate, mesotrione 0.941 0.094 Acuron (High) bicyclopyrone, mesotrione, S-metolachlor, atrazine 0.037 0.150 1.337 0.625 -None -Touchdown -Touchdown + Status -NA -glyphosate -glyphosate + dicamba + diflufenzopyr 1.0 0.138 0.053 Acuron + Atrazine + atrazine 0.75 None NA Corvus Thiencarbazone- methyl + isoxaflutole 0.033, 0.082 Degree acetochlor 1.947 Roundup P-max glyphosate 0.773 Lexar mesotrione, S-metolachlor, atrazine 0.168 1.305 Verdict saflufenacil, dimethenamid-P 0.045 0.391

Weed Control 42 DAT

Weed Control 56 DAT

Weed Control 70 DAT

Weed Control 14 DA-A

Weed Control 42 DA-A

Weed Control 7 DA-B _______________________ ________________________________ PRE PRE fb POST

Weed Control 42 DA-B

Summary – Jackson Weed control with Acuron or Acuron + atrazine was similar to that of currently available premix herbicides for corn Overall weed control from all treatments was similar 56 and 70 DAT 56 DAT weed control was <80% for all treatments, indicating a need for a follow herbicide application

Summary - Milan Residual control from Acuron or Acuron+Atrazine was similar to other PRE herbicides 14 and 42 DA-A 7 DA-B Acuron fb Status + Touchdown, Acuron fb Halex GT, and Degree fb Roundup provided greater control than Acuron, Corvus, or Lexar alone 42 DA-B control from Acuron fb Halex GT was greater than PRE alone treatments and Acuron fb Status + Touchdown provided greater control than Corvus or Lexar alone

Conclusion Acuron provides improved or similar control to currently available premix corn herbicides Sequential herbicides will still be recommended for season long weed control

Acknowledgements West Tennessee Research and Education Center Syngenta Larry Steckel Staff Syngenta Dr. James Holloway Dr. Gordon Vail

Questions?