Minnesota announced restrictions Tuesday on how farmers can use the herbicide dicamba in 2018, responding to complaints by soybean growers across the country that it harmed their crops this year.
The Minnesota Department of Agriculture set a June 20 cutoff date for applying the herbicide and prohibited applications when the temperature or forecast high for the day is above 85 degrees. The rules are meant to reduce instances of the herbicide drifting and damaging neighboring fields, which has been a problem in soybean- and cotton-growing states nationwide this year.
“We will be closely monitoring the herbicide’s performance with these restrictions in 2018,” Agriculture Commissioner Dave Frederickson said in a statement.
Farmers have used dicamba for decades, and its problems with volatility and drift were well-known. But its use has surged in the last couple years since agribusiness companies Monsanto, BASF and DuPont introduced genetically engineered, dicamba-tolerant varieties of soybeans and cotton so that farmers could use the herbicide to control tough weeds in those crops, such as pigweed, that have become resistant to other weed killers such as glyphosate, also known as Roundup.
The companies also introduced low-volatility formulations of dicamba designed to reduce evaporation and drift, but farmers who didn’t plant resistant crop varieties or use dicamba soon began reporting suspected damage anyway.
The Minnesota Department of Agriculture says it received 253 complaints from soybean growers in 49 Minnesota counties, including 55 requests for formal inspections. University of Minnesota researchers estimate that 265,000 acres across the state were affected.