A week before the 2020 presidential election, the EPA issued new instructions on the use of dicamba that it said would tame the notoriously volatile weedkiller. But complaints of damage to crops in nearby fields and to plants in parks, wildlife refuges, and residences continued to roll in, said the EPA on Thursday during a review of the herbicide.
In a pair of draft risk assessments, the EPA said that “despite the new control measures,” it received nearly 3,500 incident reports in 2021 of damage to crops that were not genetically engineered to tolerate the chemical and to “non-target plants in non-crop areas.” At the same time, the agency said there was little risk to most people from exposure to dicamba, though it identified six additional instances in which workers handling the herbicide should wear a respirator along with the required outfit of long pants, a long-sleeved shirt, socks, shoes, chemical-resistant gloves, and protective eyewear.
Farmers quickly embraced dicamba when it was introduced in 2017 as a potent new tool against invasive weeds, and since then they have used it on tens of millions of acres of soybeans, cotton, and corn annually. Just as quickly, complaints arose that dicamba evaporated too easily from where it was sprayed and wafted onto nearby crops, trees, and plants. In its October 2020 instructions, the EPA mandated a 240-foot buffer zone downwind of applications, an increase from the previous 110 feet. It also required the use of a pH buffering agent to reduce volatility, along with cutoff dates for dicamba application.
“We believe the decision today will be protective of other farmers’ crops,” said EPA administrator Andrew Wheeler, announcing the new rules and the approval of dicamba through 2025 at a farm in Georgia.
In a draft risk assessment focused on plants and animals, the EPA said it expected the 2020 restrictions to be highly effective, despite the 3,500 complaints in 2021 of damage on and off the farm — a continuation of the large number of complaints that began in 2016 when dicamba-tolerant cotton and soybean seeds went on sale.
“As generically discussed above, incidents reported for the 2021 season provide a snapshot of potential damage caused by product use, but the number of reported incidents is generally expected to underrepresent the actual number of incidents,” said the draft assessment.
Dicamba damage was seen again in the Midwest this year. “As long as we have dicamba, it’s not a question of if we ever will see off-target injury in a year — the only unknown is how extensive it will be,” Aaron Hager, an assistant professor at the University of Illinois, told Successful Farming.
The EPA compiled the draft risk assessments as part of a review of the pesticide required by law every 15 years. It said public comment on the documents would be accepted through Oct. 17.
The Center for Biological Diversity, an environmental group, said the draft risk assessment raised “grave concern about the ecological damage caused by the Trump administration’s 11th-hour approval of this dangerous pesticide.”
Large farm groups, including the American Soybean Association, the National Cotton Council, and the American Farm Bureau Federation, have defended dicamba and say complaints about the herbicide are overblown.
The draft ecological and human-health risk assessments are available here.