The rapid adoption of dicamba-resistant soybean varieties (Xtend) to control herbicide-resistant weeds and the use of dicamba herbicide postemergence in these varieties has led to numerous incidences of off-target damage to sensitive soybean varieties. The purpose of this presentation is to help growers and those in the crop protection industry understand how dicamba exposure affects non-Xtend soybean growth, development, and yield. We found that the rates required to cause injury symptoms were much lower than the rates that caused yield loss. In some instances, height reduction was a somewhat reliable indicator of yield loss, but the amount of yield loss varied quite a bit from experiment to experiment. Dicamba exposure impacts several soybean-yield parameters, including the number of fruiting nodes, seed size, seeds per pod, and pods per area. However, yield-parameter responses to dicamba exposure are compensatory and do not result in grain-yield increases.
