Department of Agronomy, Punjab Agricultural University, Ludhiana-141 004 (Punjab), India.
A pot experiment was conducted to estimate the GR50 values of new herbicides used to control the isoproturon resistant population of Phalaris minor. The pots were sprayed with 1/8 of recommended dose (R), 1/4 R, 1/2 R, Rand 2 R doses of clodinafop, sulfosulfuron and fenoxaprop-p-ethyl and 1/2 R, R, 2 R, 3 Rand 4 R of isoproturon at 35 days after sowing. Isoproturon at 50% higher than the recommended dose was not able to control 50% population on mortality basis. Isoproturon, clodinafop, sulfosulfuron and fenoxapropp-ethyl recorded 1451.85, 2.45, 2.70 and 3.4 g ha−1 as the GR50 values, respectively, on mortality basis. On basis of dry matter accumulation, the GR50 values were found to be 1403.40, 1.84, 2.5 and 4.9 g ha−1 for isoproturon, clodinafop, sulfosulfuron and fenoxapropp-ethyl, respectively.
