EPA Release of Dicamba Labels for Xtend Soybean Systems

By John Wallace and Dwight Lingenfelter

EPA's release of new dicamba labels last week should help growers make more informed decisions about soybean trait selection and available herbicide options for the 2021 growing season. Three dicamba products (XtendiMax, Engenia, Tavium) now have a 5-year federal label for over-the-top use in Xtend soybean. The new labels have additional requirements and restrictions beyond the previous labels. Noteworthy changes include:

• Dicamba applications are not allowed after June 30. XtendiMax and Tavium also restrict applications based on soybean growth      stage,which serves as the cut-off date if it occurs before June 30. Growth stage cut-offs include R1 for XtendiMax and V4 for Tavium. Tavium is pre-mixed product that contains dicamba and s-metolachlor.

• Dicamba applications must include a 240 foot downwind buffer for non-sensitive areas.Downwind buffers can be reduced to 110 foot buffer if a qualified hooded sprayer is used.

• Dicamba applications will require pH-buffering agents to reduce volatility potential. XtendiMax and Tavium require use of a qualified pH buffering adjuvant or volatility-reducing agent and a drift-reduction agent in every application. Engenia only requires use of a pH buffering adjuvant. An applicator will need to visit each company's support websites to identify pH buffering, volatility reducing, and drift reduction products that are permitted.

With herbicide and soybean trait registration issues resolved for at least for the 2021 growing season, we now have a clearer picture of postemergence herbicides labeled for use in alternative soybean seed trait systems (Table 1).

Table 1. Herbicides labeled for herbicide-resistant soybean systems.

Perhaps it is worth a reminder that dicamba and 2,4-D are not interchangeable, which means dicamba will kill Enlist soybeans and 2,4-D will kill Xtend soybeans if applied over the top. It is also worth noting that when using these soybean trait systems, we recommend use of dicamba and 2,4-D to improve pre-plant burndown herbicide programs but limiting postemergence use to reduce the potential for off-target movement and selection pressure for resistance. We will continue to provide updates on the status of these herbicide labels if circumstances change and will provide recommendations for their stewardship in Pennsylvania field crops in the lead up to next growing season.