Production Blog

Dicamba Research Download

A sign of the times as some growers marked soybean fields last year hoping to alert applicators of sensitive varieties within. New studies are showing more about the characteristics of new dicamba formulations. (DTN photo by Pamela Smith)

DECATUR, Ill. (DTN) -- Every so often a written work comes along that makes me wince. That's exactly what today's post from the University of Missouri did, because it is just that good. I wish I'd written it.

Instead, I'm recommending that everyone using herbicides in an agricultural cropping system read the paper by Missouri weed scientists Kevin Bradley and Mandy Bish: Five Things We've Learned about Dicamba. It summarizes lessons these two scientists and their graduate students have learned over the past several years of researching the herbicide.

Read it here:…

Just do it. Excuses that you've taken the required training or your crop will be protected because you are planting Xtend varieties or you only intend to use dicamba in a pre-emergence aren't good enough.

Bradley and Bish take findings well beyond mere soybean sensitivity and pull no punches. Volatility exists in the new dicamba formulations and can be detected in the air well beyond initial application, according to their studies.

Missouri, and other universities, have found that glyphosate can lower spray tank pH. If the pH of the tank mixture becomes too low, it can cause dicamba to dissociate to the acid form, which is the most volatile form of dicamba. Missouri studies have also shown low soil ph can lead to dicamba volatility from the soil surface.

Temperature inversions are common and lead to off-target movement, they confirm. This paper explores that in more detail:…

The item that might surprise growers most is Missouri's finding that burndown applications of dicamba products can still be problematic. The thought that these new herbicides are less likely to move off-target and cause injury when applied earlier (April and May) in the season, when temperatures are cooler, has been a popular thought process.

"And we still believe this to be true; especially with regard to the likelihood of injuring your neighbor's non-Xtend soybean. However, less likely doesn't mean not possible," the authors state. "Last season, we received more calls and complaints in April and May about off-target dicamba movement to specialty crops and trees than at any other time during the season."

It is the applicator's responsibility to understand the behavior of this herbicide -- and they are liable when it moves off target. These studies can help.

For further reading on the new dicamba label changes go to:…"

Pamela Smith can be reached at

Follow her on Twitter @PamSmithDTN



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