EPA reconsiders dicamba herbicide despite drift and resistance concerns

The U.S. Environmental Protection Agency is proposing to reapprove the use of dicamba, a controversial herbicide used in genetically engineered crops, drawing criticism from public health advocates and environmental groups over its history of crop damage, herbicide resistance, and regulatory lapses.

Public comments on the proposal are open until August 22, 2025, as the agency weighs three new registrations submitted by Bayer, which acquired Monsanto and now markets dicamba-tolerant seed and herbicide combinations. The proposed changes include revised product labels and claims of low-volatility formulations aimed at mitigating off-target drift—a primary concern that has led to extensive crop damage in past seasons.

Dicamba has been used in combination with herbicide-tolerant crops such as soybeans and cotton since the mid-2010s, following a surge in glyphosate-resistant weeds. However, its tendency to volatilize and drift onto neighboring farms has prompted widespread legal challenges and regulatory setbacks. Courts vacated previous EPA authorizations in 2020 and again in 2024, citing failure to adequately manage risks, leading to a pause in dicamba spraying for the 2025 growing season.

Despite these rulings, EPA is now reconsidering its stance. The agency’s proposal allows for dicamba applications before planting, at planting, and post-emergence. Proposed label conditions include a 240-foot downwind buffer—subject to various exemptions—as well as temperature limits during and after application. Critics argue that these safeguards are insufficient, especially under warming climate conditions that intensify dicamba volatilization.

The American Soybean Association has supported the continued use of dicamba, calling it a “critical crop-protection tool” in managing resistant weeds like Palmer amaranth. Bayer has echoed these sentiments, emphasizing the herbicide’s role in enhancing yield potential and weed control for U.S. farmers.

However, opponents, including advocacy group Beyond Pesticides, argue that dicamba’s risks to human health, biodiversity, and neighboring farms outweigh its benefits. The group warns that the EPA’s risk-benefit analysis neglects viable organic alternatives that avoid herbicide dependence and are already in commercial use.

The renewed regulatory effort comes as pesticide drift remains a contentious issue in agricultural regions. Dicamba, with its high vapor pressure, can move off-target as either droplets during application or as vapor afterward, affecting crops, wildlife, and rural communities. Disputes over drift damage have led to hundreds of lawsuits and even violent confrontations among farmers.

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), EPA is required to ensure that pesticides do not pose “unreasonable adverse effects on the environment.” Opponents of the proposal argue that EPA is failing to meet this legal threshold by considering expanded use of a herbicide already linked to documented harm and ineffective resistance management.

The EPA’s docket for public comment is available under reference [EPA-HQ-OPP-2024-0154-1233] on Regulations.gov. Final decisions are expected following the close of the comment period.