Effect of Different Herbicides Alone and in Mixture on the Control of Isoproturon-Resistant and Susceptible Populations of Phalaris minor

Isoproturon at 1.0 kg, metoxuron at 1.6 kg and methabenzthiazuron 1.4 kg ha⁻¹ applied at 3-leaf stage provided more than 80% control of both susceptible (S) biotypcs (R1 and H2) of P. minor: however, these herbicides were ineffective against resistant (R) biotypes (H3, KR1 and UP1) even at higher doses. Mon-48549 at 25 and 50 g, and Foe-5043 at 300 and 600 g ha⁻¹ also did not control this weed satisfactorily. Performance of diclofop and metribuzin was also erratic against R and S biotypes. Clodinafop at 60 g, fenoxaprop at 120 g, sulfosulfuron at 25 g and tralkoxydim at 350 g ha⁻¹ applied at 3-leaf stage resulted in 82–95% reduction in the dry weight of R as well as 5 biotypes of P. minur: Metribuzin at 200 and 400 g ha⁻¹, and Mon-48549 at 25 and 50 g ha⁻¹ caused 15 to 30% phytotoxicity to wheat. Metribuzin either alone or in mixture caused phytotoxicity to wheat crop without adding to weed control efficiency (WCE).