Response of triallate-resistant wild oat (Avena fatua) to alternative herbicides

Wild oat populations resistant to triallate have been identified in Alberta. Dose response experiments were conducted in the greenhouse to determine if triallate-resistant wild oat was controlled by other selective wild oat herbicides. Triallate-resistant wild oat populations were effectively controlled by atrazine, ethalfluralin, fenoxaprop-P, flamprop, imazamethabenz, and tralkoxydim. EPTC and cycloate, which are chemically related to triallate, differed in their efficacy on triallate-resistant wild oats. EPTC at the 0.25x field use rate was more efficacious on triallate-resistant than triallate-susceptible wild oat. In contrast, cycloate at the 0.25 to 0.5x field use rate was less efficacious on triallate-resistant than susceptible wild oats. At higher rates, both EPTC and cycloate killed triallate-resistant wild oat populations. Growers have several herbicide choices to selectively control triallate-resistant wild oat in prairie field crops but should plan to rotate herbicides among different chemical families and adopt integrated weed management practices to reduce the risk of these wild oat populations developing resistance to other wild oat herbicides.