Research shows that “secondary movement” of dicamba occurs in more ways and more unpredictably than previously known, University of Missouri weed scientist Kevin Bradley said last week at Iowa State University’s Integrated Crop Management Conference. 

However, he said, the greatest problems with off-target damage typically are correlated with the volume of dicamba sprayed.

“Greater dicamba concentration in the air is always correlated with the greater (amounts) that we sprayed dicamba in that location, regardless of where that location is,” he said. 

In Missouri, the most problems with off-target damage have been in the Bootheel region, where farmers plant a high percentage of dicamba-tolerant soybean and cotton ...