Soybean field with barn

(Photo: Iowa Soybean Association)

Dicamba application deadline pushed back

February 23, 2023 | Jeff Hutton

The Environmental Protection Agency (EPA) has trimmed back the window for farmers in Iowa and other Midwestern states is using a weedkiller under scrutiny for drifting away from where it is sprayed.

This month, the EPA announced that the 2023 deadlines for farmers to spray dicamba in Iowa, Illinois and Indiana is now set for June 12, compared to June 20 last year. The EPA approved a June 20 deadline for South Dakota, instead of June 30 last year.

According to the EPA, the organization approved labeling amendments that further restrict the use of dicamba – the Iowa, Illinois and Indiana amendments were requested following discussion with the three states.

Officials with the EPA say the earlier dicamba application deadline is designed to reduce the “potential for dicamba to volatize and drift off-site.”

Frustration in Iowa

The news of the change received mixed reactions from Iowa Agriculture Secretary Mike Naig and the Iowa Soybean Association.

“Given that this product is under activist attack in the courts, I’m glad that farmers will continue to have access to this critical crop protection tool that they depend on,” he says. “However, I’m once again frustrated by EPA’s lack of urgency and decision to make this change so close to spring planting.”

ISA Director of Public Affairs Michael Dolch agrees with Naig.

“We are pleased that soybean farmers will have continued access to the important weed management tool,” he says. “While we understand and appreciate EPA’s desire to curb potential risks associated with application, the timing of this decision is frustrating and problematic for farmers who are already committed to a specific cropping system. If the current trend of earlier soybean planting continues, the V4 growth stage cutoff is certainly a concern. We’ll continue to ensure folks are aware of the change as we quickly approach the growing season.”

EPA says the changes are designed to reduce risks adding that some scientists consider an earlier deadline to be safer because warmer temperatures can increase the risk for dicamba to drift from where it is sprayed.

Some farmers and scientists have reported problems with dicamba drifting and causing damage to nearby plants that are not genetically modified to resist the herbicide.

According to the EPA, other requirements include registrants must add the amended labeling to their training and educational materials and disseminate this information to pesticide authorities and agricultural extension services to assist users in their local area. These and other requirements are outlined in the terms and conditions of the amended registration.

These amendments follow amendments EPA approved for Iowa in March 2022.

To view the amended labeling, visit docket EPA-HQ-OPP-2020-0492 at

For more information on dicamba, see: or