Dicamba and the Treadmill of Herbicide Resistance
Many reports have circulated the U.S. concerning widespread dicamba injury to off-target crops, particularly in the Mid-South and Midwest, according to an article on IntegratedWeedManagement.org. Based on a national survey led by Kevin Bradley, weed scientist at the University of Missouri, 3.1 million acres of crops were reported injured by dicamba in 2017, which was legally applied to dicamba-resistant soybeans for the first time in 2017.
According to weed specialists at the University of Minnesota, this issue is concerning for several reasons beyond injury to crops. These include neighbor disputes about drift, pressure to purchase dicamba-resistant beans as a defensive tactic, and the complicated dicamba label and associated regulations. We have also seen misleading manufacturer claims that dicamba-related technology is the stand-alone solution for herbicide resistant weeds. There is no silver bullet for herbicide resistant weeds.
If growers come to over-rely on dicamba products, history suggests that the cycle of resistance will continue, and we will face increased weed resistance to dicamba as we have with glyphosate, triazine, and ALS-inhibitor herbicides. It is important to remember that there is still no silver bullet for resistant weeds, and dicamba is no exception.