Evaluation of dicamba volatilization when mixed with glyphosate using imazethapyr as a tracer.

Expansion of dicamba-resistant crops increased the frequency of off-target movement issues, especially in the midsouthern United States. Six field trials were conducted over two growing seasons with the purpose to determine the contribution of volatilization and physical suspension of particles to the off-target movement of dicamba when applied with glyphosate and imazethapyr - a non-volatile herbicide used as a tracer for physical off-target movement. Applications included dicamba at 560 g ha, glyphosate at 1260 g ha, and imazethapyr at 105 g ha.