Author(s)

Matthew G. Underwood, Nader Soltan^*, David C. Hooker, Darren E. Robinson, Joseph P. Vink, Clarence J. Swanton, Peter H. Sikkema

Department of Plant Agriculture, University of Guelph, Ridgetown, Canada.

Traditional two-pass weed management strategies need to be compared with new strategies in glyphosate/dicamba-resistant soybean. Weed control, soybean yield, partial profitability and environmental impact (EI) were evaluated in glyphosate/dicamba-resistant soybean using dicamba applied alone or in a tank-mix with dimethenamid-P applied preemergence (PRE). Trials were conducted at three locations during 2014 and 2015. Several PRE herbicides provided excellent control of broadleaf and grass weeds. Dicamba provided > 91% control of broadleaf weeds, and the addition of dimethenamid-P improved grass control. All weed species at the trial locations were controlled > 94% following a postemergence (POST) application of glyphosate. Weed interference reduced soybean seed yield 33% where no herbicide was applied. A single POST application of glyphosate had the lowest EI. Several treatments improved early-season weed control and reduced early-season weed density and biomass compared to glyphosate and had similar EI values. In this study, there was no benefit to yield or partial profit by including a PRE herbicide for weed management; however, the inclusion of multiple modes-of-action in a herbicide program may reduce the selection for herbicide-resistant weeds.

Density, Environmental Impact, Injury, Profit Analysis, Tillage, Yield, Weed Control

Underwood, M. , Soltan, N. , Hooker, D. , Robinson, D. , Vink, J. , Swanton, C. and Sikkema, P. (2017) Weed Control, Environmental Impact, and Net-Profit of Two-Pass Weed Management Strategies in Dicamba-Resistant Soybean (Glycine max) Using Conventional Tillage. American Journal of Plant Sciences, 8, 3414-3428. doi: 10.4236/ajps.2017.813229.