By Julie Tomascik
Editor

The U.S. Environmental Protection Agency (EPA) reapproved the herbicide dicamba for over-the-top (OTT) applications on genetically modified cotton and soybeans for the 2026 and 2027 growing seasons.

The agency said the decision responds to requests from farmers who face challenges from herbicide-resistant weeds that threaten crop yields.

“This action reflects [the Trump] administration’s commitment to ensuring farmers have the tools they need to succeed while protecting the environment with the strongest safeguards ever imposed on OTT dicamba use,” EPA said in a press release.

Dicamba has been used for decades to control broadleaf weeds, but its OTT use has drawn scrutiny in recent years due to concerns about volatility and off-target movement that can damage neighboring crops and sensitive plants.

As part of the announcement, EPA said it addressed those concerns by tightening use restrictions to reduce drift, minimize volatility and protect surrounding ecosystems.

Under the updated label, the maximum application rate per acre was cut in half.

EPA also imposed temperature-based application limits designed to reduce risk during conditions when dicamba is more likely to volatilize. When forecasted temperatures fall between 85- and 95-degrees Fahrenheit, applicators may treat only up to half of their untreated dicamba-tolerant cotton or soybean acres in a county on a given application day, with remaining acres delayed for at least two days.

Applications are prohibited entirely if temperatures are forecasted to reach 95 degrees or higher on the day of or the day after treatment.

Additional drift-reduction measures are also required. An approved drift reduction agent must be added to every tank mix to produce larger, heavier droplets that are less likely to drift off-target.

A 240-foot downwind spray drift buffer also must be maintained during applications to protect adjacent areas, and dicamba use is prohibited if dicamba-sensitive crops or plants are present in downwind areas.

EPA tightened application parameters, requiring wind speeds between 3 and 10 miles per hour, coarser spray droplets and a spray release height no higher than two feet above the ground or crop canopy and aerial application is prohibited.

“Applicators who fail to follow label directions are subject to significant penalties under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), including civil fines and, in cases of knowing violations, criminal prosecution,” the agency said in the release. “EPA will work with state enforcement to actively monitor compliance, and violations will be met with serious consequences.”

EPA said it will continue monitoring performance of the chemistry and make adjustments if needed.

The restricted-use pesticide may only be applied by certified applicators who complete annual training specific to OTT dicamba use.

Texas Farm Bureau President Russell Boening said the science-based approval of dicamba product labels provides needed certainty for growers.

“This tool helps maintain competitiveness by preventing resistant broadleaf weeds from increasing costs and pressuring yields. In a tough economic environment, it offers growers reliable options for effective weed management while facing variable weather and diverse growing conditions across Texas,” Boening said. “The approved labels provide clear requirements that emphasize stewardship and responsible use, giving farmers the regulatory certainty needed to plan for the growing season while protecting neighboring crops.”

Dicamba’s regulatory path has been contentious. Prior EPA approvals for OTT use were twice vacated by federal courts, most recently in 2024, creating uncertainty for farmers heading into recent growing seasons.

Dicamba products, including XtendiMax, Engenia and Tavium, are commonly used to control weeds such as Palmer amaranth, which has become increasingly difficult to manage with other herbicides. Because the products can be applied over dicamba-tolerant cotton and soybeans, they provide growers with added flexibility later in the growing season.

XtendiMax is marketed by Bayer, Engenia by BASF and Tavium by Syngenta.