EPA restricts dicamba herbicide

In the wake of thousands of complaints of damage to crops in the U.S. from the herbicide dicamba drifting off of neighboring fields, the Environmental Protection Agency and pesticide makers have reached an agreement to impose restrictions on the herbicide’s use.

Dicamba products sold for the 2018 growing season will be classified as restricted use, meaning they can only be applied by a certified applicator with special training. Other changes include limiting dicamba spraying to when winds are less than 16 km/hour, restricting spraying to certain times of the day, and requiring farmers to keep records of dicamba use.

Farmers are increasingly spraying dicamba on soybeans and cotton that have been genetically engineered to tolerate it, as weeds are becoming resistant to other herbicides such as glyphosate. But soybeans that have not been genetically engineered to tolerate dicamba are particularly susceptible to its damage.

State agencies in Arkansas, Illinois, Missouri, Ohio, and Tennessee worked with EPA and pesticide manufacturers to investigate complaints of dicamba damage to nontolerant crops since 2015. Dicamba manufacturer Monsanto is confident that increased training and record keeping will “address the main causes of off-target movement,” says Ty Vaughn, Monsanto’s global regulatory lead. EPA says that it will monitor whether the changes reduce dicamba damage to nontarget crops as the agency decides whether to allow use of the herbicide beyond 2018.