The U.S. Environmental Protection Agency recorded nearly 3,500 reports of off-target dicamba movement in 2021, despite stricter rules enacted in 2020.
The EPA's report on 2021 dicamba usage and incidents alleges the herbicide damaged cotton and more than 1 million acres of soybeans that weren't dicamba-tolerant; other crops, including sugarbeets, rice, sweet potatoes, peanuts, grapes, cucurbits, vegetables, fruit trees and caneberries; ornamental plants; state parks; and wildlife refuges. The report from the EPA says the incidents in food crops reportedly occurred in Arkansas, Illinois, Kansas, Missouri, North Dakota, Nebraska, Ohio, South Dakota, Tennessee and Texas.
“Overall, incidents are mostly associated with wide area (10’s to 100’s of acres per incident) damage to non-DT soybean plants and localized small-scale damage to lawns,” the report reads in part. “A pronounced increase in the overall number of reported dicamba incidents allegedly associated with damage to non-target plants started around 2016 and appears to be linked to the introduction of DT plants and over-the-top (OTT) applications to those crops.”
In 2020, the EPA enacted control measures to manage off-site movement of dicamba, including requiring an approve pH-buffering agent to be tank mixed with OTT dicamba products prior to application and restricting the timeframe for OTT application of dicamba on soybeans and cotton. However, in March, the EPA said incidents from the 2021 growing season showed little change in number, severity or geographic extent compared to seasons prior to the stricter rules.
An EPA assessment indicates that off-target applications exceeding the level of concern for plants can range more than 1,000 down-wind of spray applications and 2,600 feet downwind of aerial applications. The main driver for dicamba to exceed the level of concern is a combination of spray drift and volatility.
The EPA is currently taking public comment on the ecological risk assessments for the registration review of dicamba online. The deadline for public comments is Oct. 17.