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Research Suggests The Key To Stopping Dicamba Drift Is At The Molecular Level

Soybeans like these in central Missouri are often treated with Dicamba.
Jonathan Ahl
St. Louis Public Radio
Soybeans like these in central Missouri are often treated with Dicamba.

Researchers at Washington University in St. Louis are looking at the weed killer dicamba, specifically how its molecules bond with other chemicals that are applied to fields at the same time.

The belief is that how those hydrogen bonds form, or don’t form, could lead to a chemical fix to the problem of dicamba drifting away from where it's applied onto other fields.

Dicamba has come under criticism for years for killing crops, vegetables and houseplants miles away from where it is applied to crops, specifically soybeans and cotton.

Bayer, the maker of dicamba, has consistently said drift is not an issue when it is applied correctly following the label instructions.

“I think, ultimately the work we’re doing to build a better molecular picture, I think, would hopefully improve and inform the design of better chemicals,” said Kimberly Parker, assistant professor in the Department of Energy, Environmental & Chemical Engineering at Washington University.

Parker said many variables affect dicamba drift, chief among them are weather conditions like wind and humidity. But she said the initial findings in her team’s research suggest closer study of molecular bonds could inform better and safer practices.

“Why that’s interesting is because if we think about controlling volatility in the future, we may be going down the wrong path if we don’t really understand what are the actual processes at play,” Parker said.

Bayer, in a statement, said the company reviews all research conducted on its products, but also said the Washington University study “did not look at our low-volatility formulation, XtendiMax herbicide with VaporGrip Technology. Bayer developed VaporGrip Technology to help limit the volatility potential of dicamba.”

Bayer’s statement also pointed at the new label instructions developed when the Environmental Protection Agency approved the weedkiller for 2020.

“The new EPA-approved product label for XtendiMax herbicide includes some changes to further ensure growers can use the product successfully,” the statement said.

Those changes include updated guidelines on when dicamba can be spread and under what weather conditions, as well as specific guidance on what additives can be included.

Bayer’s proprietary formulations are part of the problem, according to Parker. She said one of the goals of the research is to help everyone concerned with dicamba have the best information.

“So that the discussions that are happening, broadly among many different stakeholders, would be informed by publicly accessible science,” Parker said.

Parker said more research would be needed to come up with better options for dicamba application. Her team’s initial findings were published in the journal Environmental Science and Technology.

Follow Jonathan on Twitter: @JonathanAhl

Jonathan Ahl is the Newscast Editor and Rolla correspondent at St. Louis Public Radio.