Ensuring Success With Dicamba in 2018

For many soybean producers, the 2017 growing season will be a hard one to forget. Widespread dicamba use in dicamba-resistant soybeans caused equally widespread off-target damage. The United States Environmental Protection Agency (EPA) has issued amendments to XtendiMax, Engenia, and FeXapan labels, but Aaron Hager says the amendments won’t be enough to ensure success in the 2018 growing season.

“The intent of these label amendments is to reduce sensitive plant species exposure to dicamba primarily through physical movement (i.e., drift during the application or particle movement during temperature inversions) or via dicamba residues dislodged from application equipment, but because labels don’t include language to prevent volatility, there will still be risk of off-target exposure,” says Hager, weed scientist in the Department of Crop Sciences at the University of Illinois.

As with any herbicide, application must follow all label directions and minimize off-target movement of spray particles. It is the responsibility of the applicator, whether private or commercial, to follow all label directions before, during, and after the application of dicamba. Hager notes that strict adherence to label instructions is in the best interest of maintaining the availability of this technology.

Hager shares his thoughts for what success or failure for dicamba might look like in 2018.

“For me, success is the use of dicamba as one component of an integrated weed management program that emphasizes proper selection and application of effective soil-residual herbicides and only EARLY postemergence applications of dicamba (i.e., approximately 14 days after planting), followed by implementation of other herbicide or non-herbicide tactics to ensure zero weed seed production,” he says. “Failure would be the singular use of dicamba as a postemergence herbicide in dicamba-resistant soybean.”

He provides the following steps to achieve success with dicamba in 2018.

1. Plant dicamba soybean seed into a weed-free seedbed. This can be achieved through the use of preplant tillage, effective burndown herbicide(s), or a combination of tillage and burndown herbicides.
2. Select and apply within 7 days of planting a soil-residual herbicide that targets your most problematic weed species. If desired (and labeled), add dicamba and an appropriate buffer. Soil-residual herbicides that offer excellent, good, and acceptable control for waterhemp and Palmer amaranth are listed on the Bulletin.
3. Scout fields 14 days after planting. Apply dicamba at 0.5 lb ae/acre when weeds are less than 3 inches tall and when conditions allow for the application. Consider adding an approved soil-residual herbicide to the tank mix.
4. Scout treated fields 7 days after the dicamba application. If control is not complete or another flush of weeds has emerged, consider using non-dicamba options for complete control. Examples include alternative herbicides, cultivation, and hand rogueing. The goal should be zero weed seed production.

Additional details can be found in Hager’s original post on the Bulletin, athttp://bulletin.ipm.illinois.edu/?p=4065.

Source: University of Illinois