New Cut-off Date for Over-the-top Dicamba use in Iowa for 2023

By Prashant Jha

On February 16, the U.S. Environmental Protection Agency (EPA) approved the label amendments that further restrict the use of over-the-top (OTT) dicamba in Iowa, Illinois, and Indiana. For the 2023 season, the revised federal labels for XtendiMax, Engenia and Tavium contains a new cut-off date restriction for OTT dicamba use:

• No spraying on dicamba-tolerant (DT) soybeans in Iowa, Illinois and Indiana after June 12 or V4 growth stage, whichever comes first.

This restriction was proposed by the product registrants and approved by EPA in an effort to reduce off-target movement of dicamba most likely due to applications to be made at decreased temperatures and reduced soybean growth stage earlier in the season. June 12 cut-off date used in Minnesota for the 2022 growing season served as a model demonstrating significantly reduced off-target improvement.

In addition to the above amendment, applicators must follow all other restrictions for the use of those dicamba products in dicamba-tolerant soybean, as mandated by the product label. One of these restrictions include additional measures to protect the endangered species in specific counties of Iowa. Adherence to the new EPA application guidelines in soybeans, responsible dicamba usage in corn and strict equipment sanitation procedures should lead to drastically fewer cupped soybeans fields in the 2023 growing season.

With an earlier cut-off date in 2023, growers need to be more proactive in managing late-emerging weeds, predominantly waterhemp, in their soybean fields. A significant proportion of waterhemp can still emerge after June 12 or V4 stage of soybean. A layered soil residual herbicide program would be very crucial this season to control late-emerging waterhemp in soybean and reduce/prevent seed bank additions. This will be more important considering the widespread occurrence of herbicide-resistant waterhemp populations in Iowa soybean fields.

Here are links to each herbicide product with its label and application requirements for 2023. 

• XtendiMax
• Engenia
• Tavium