Response of isoproturon-resistant Phalaris minor to some dinitroaniline herbicides.

Field and pot experiments were carried out to evaluate the response of herbicide-resistant Phalaris minor to some of the dinitroaniline herbicides. The results of field experiments indicated that pre-emergence application of oryzalin, pendimethalin and trifluralin gave excellent control of isoproturon-resistant P. minor. Post emergence application of these herbicides after first irrigation at 3 WAS at their reduced rates, tank mixed with isoproturon also gave satisfactory results. Tank mixing of dinitroaniline herbicides with isoproturon may be desirable as these treatments gave boad spectrum control of weeds. None of the treatments had any phytotoxic effect on crop as reflected by the data on grain yield of wheat. Pot experiment with three resistant and one susceptible biotype did not reveal the existence of cross resistance to pendimethalin or trifluralin. The role of dinitroaniline herbicides in the overall management of herbicide-resistant P. minor is discussed.