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4 Takeaways From 2016’s Missouri Dicamba Disaster

Dicamba does a number on non-dicamba-tolerant soybeans. Here are ways to prevent it in 2017.

Last summer, some applicators used unlabeled and illegal dicamba formulations on dicamba-tolerant soybeans in Missouri. Estimates are that 100,000 acres of Missouri soybeans were damaged in this manner.

For 2017, here are 4 takeaways to prevent this from happening again. They’re from Kevin Bradley, University of Missouri Extension weed specialist.

Q: What’​s the major takeaway from this chemical drift disaster?
Bradley: The number one factor that contributed to these crop injuries is the lack of appreciation for the inherent sensitivity of soybeans to a low concentration of dicamba. You can get away with a little drift of glyphosate or Liberty. But not dicamba.

Just as an example of the sensitivity, 8 fluid ounces of dicamba mixture left in a 1,200-gallon spray tank will be enough to cause visible foliar injury to soybean plants. One gallon left in a tank will give significant yield loss. And the yield damage is more if the injury occurs later in the season. Early in the season, the soybeans may grow out of the injury. But not when they are in the reproductive stage.

Q: What about the impact on soybean seed production, on seed intended to be planted next year?
Bradley: We know that dicamba injury this year can affect the seeds planted next year. There can be a 50% reduction in seed emergence the next year. And injury hits the plants early that year, as early as 14 days after emergence.

Q: Where can I get more information on this dicamba issue?
Bradley: Most of the information we know and that we have shared publicly is on our university weed science website at

Q: What about temperature inversions? How can I know when not to spray fields?
Bradley: You have to make yourself aware of weather conditions and avoid those times when the risk is high. Also, there’s a website,, that is a voluntary communication tool that enables crop producers, pesticide applicators, and beekeepers to work together to protect crops. You can go there and find your field location and see what is nearby for crops, pollinators, and other things that could present a risk.


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