More pieces needed to solve dicamba drift puzzle


As the dicamba drift situation unfolds in soybean growing areas of North America, with millions of acres affected, there are some serious questions that will need to be answered in the coming months.

  • How extensive was the damage?
  • What were the factors that led to dicamba herbicide ending up in places where it wasn’t supposed to go?
  • New dicamba formulations are less volatile than old versions (that have been used for years in other situations), but has the vapour drift risk been understood correctly?
  • The education campaign for spraying these new formulations has been unprecedented, so would additional training and awareness of best management practices help minimize cases due to misapplication or improper tank cleanout?
  • And ultimately, what can be done to mitigate this off-target movement and maintain dicamba as a tool for managing herbicide resistant weeds?

“There’s a story to be told, and right now we only have a few pieces of that puzzle or story. In the next three or four months there’s going to be a lot more information coming available that will help tell the accurate story of why this happened and precautions that we can take next year to avoid having this happen again,” says Rich Zollinger, weed extension specialist with North Dakota State University, in the interview below.

Rich Zollinger, NDSU

“We would like to think that industry, the chemical companies, and the universities are all on the same side. I would hope to think that we as a profession, as a society, are past the point of denial,” he continues.

While much of the attention, at least initially, focused on injury reports in southern states like Arkansas and Missouri, Zollinger says that was largely due to crop staging. In North Dakota, he says there’s at least one soybean field damaged by dicamba drift “in every part of the soybean growing area.” In some cases, dicamba was applied during the week of June 20th, but symptoms didn’t appear until three or four weeks later, he says.

To the north, Manitoba’s agriculture department doesn’t hear about every drift case, but they’ve confirmed at least eight cases of dicamba injury in soybeans. How it happened is unclear in most instances, but they say at least one field showed definite symptoms of vapour drift.

It’s a similar story in Ontario, where there have been anecdotal reports of dicamba injury in soybeans, but it’s difficult to determine the extent and how the injury happened as cases are being dealt with between the parties involved without being reported to the provincial government.

Back in North Dakota, Zollinger believes most growers have applied the herbicide according to label directions and followed the recommended best management practices, leaving questions about what’s happening with the droplets after they are no longer in the farmer or applicator’s control.

“We don’t have all the answers. We hope we can get more of this information on the physical properties and how it responds to the environment in the next few months so we can tell a complete story when we explain it to the growers,” he says.

Zollinger says he’s confident dicamba technology will still be a tool for fighting weeds going forward, but… “only if we all, and when i say all, that’s the growers, the industry, academia, the seed companies, come together and we all have the same objective — to understand why it happened and what we can do to minimize having it happen again.”

Listen to our chat with Rich Zollinger on RealAg Radio (full Tuesday show here):


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