Pesticide Research Journal

Bispyribac 30 g ha⁻¹ behaving statistically alike with its different doses (20 and 25 g ha⁻¹) and with farmer's practice, and cyhalofop butyl followed by (fb) 2, 4-D resulted in significantly lower count of Echinochloa colona. Bispyribac effectively controlled Digitaria sanguinalis. Cyhalofop-butyl fb 2,4-D remaining at par with farmers’ practice resulted in significantly lower count of Panicum dichotomiflorum. Bispyribac and butachlorfb 2,4-D/metsulfuron-methyl effectively reduced the count of Commelina banghalensis and Cyperus iria. All treatments were equally good in reducing the count of Ageratum conyzoides. Weeds when allowed to grow throughout crop season caused 48.2% grain yield reduction. Grain yield obtained with the application of bispyribac 30 g ha⁻¹ was 7.9% higher over farmers’ practice. Grain yield of rice was positively associated with plant height, panicle length, spikelets panicle⁻¹ and effective tillers and was negatively associated with weed count and weed biomass. Every g m⁻² increase in weed dry weight would result in 15 kg ha⁻¹ fall in the grain yield of rice. Bispyribac at 30 kg ha⁻¹ resulted in highest net returns due to weed management. Cyhalofop butyl fb metsulfuron methyl gave the highest net profit rupee⁻¹ invested. Bispyribac 30 g ha⁻¹ resulted in highest weed control efficiency (85.7%), crop resistance index and herbicide efficiency index. Weed index was lowest in bispyribac 30 g ha⁻¹. Farmers’ practice had lowest weed management index (WMI) followed by cyhalofop fb 2,4-D, and bispyribac 30 g ha⁻¹.