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Minnesota Soybean Task Force Suggests a Temperature Cutoff for Dicamba
State officials should set a cutoff date for spraying dicamba on genetically engineered soybeans as well as a temperature cutoff of 85°F. to reduce greatly the chance of damage to neighboring crops, says a task force of the Minnesota Soybean Growers Association. The state restrictions would be in addition to the more stringent rules recently adopted by the EPA.
“Minnesota farmers want to embrace new technologies while continuing to be good neighbors with other farmers and good stewards of the land,” wrote task force chair Bob Worth in a letter to state agriculture commissioner Dave Frederickson. “We feel these changes will help our farmers accomplish both goals while preventing weed resistance through the certified use of new technologies.”
The task force proposed a one-sentence addition to Minnesota’s dicamba regulations: “Do not apply if predicted, or actual temperature high is 85°F. or above.” Worth said research showed that vapor volatility, or drift, “increases as air temperature increases and humidity decreases. Daytime temperature is the primary driver of increased volatility…60% of variation associated with dicamba vapor drift (is) attributed to increased temperature, especially above 85°F.”
Pesticide companies, university scientists, state officials, and growers should collaboratively agree on a cutoff date for spraying dicamba, said the task force.
The Missouri state agriculture department has set a dicamba cutoff of June 1 in 10 southeastern counties and July 15 for the rest of the state. Missouri acted first on BASF’s version of the herbicide and said it would set similar limits for Monsanto and DuPont formulations. The EPA decided to restrict dicamba application to daytime hours and when the winds do not exceed 10 mph. It also requires applicators to go through special training on use of the herbicide.
To read a Minnesota Soybean Growers Association release or the three-page task force letter, click here.