Efficacy of imazethapyr and other herbicides on weed growth and yield of kharif blackgram

A two year field experiment was conducted during the the kh arijseason of 2014 and 2015 at Agricultural Farm, Institute of Agriculture, Visva-Bharati, Sriniketan, West Bengal, with blackgram variety 'WBU- 108′ to study the effect of imazethapyr and other herbicides on weed growth, productivity and economics of kh ari^blackgram. The experiment was laid out in a randomized block design with three replications and eight treatments. From the investigation it revealed thai Digitaria sanguinalis among the grasses; Cyperus iria among the sedges and Ludwigia parviflora and Croton bonplandianum among the broadleaved weeds were predominant throughout the cropping period. Higher doses of imazethapyr (75, 100 and 125 g ha1) applied at 20 DAS effectively controlled the grasses, broadleaved and sedges in blackgram at 45 DAS. Yield reduction due to weed competition was to the extent of 26–29% in kh ari/blackgram. Lower values of weed density, total weed dry weight, weed index and higher values of weed control efficiency, seed yield, net return and return per rupee invested were registered with application of imazethapyr at 75 g ha"1 at 20 DAS which was at par with by imazethapyr at 100 g ha"1 at 20 DAS. These treatments may be recommended for managing complex weed flora and obtaining higher yield and net return of kh arif blackgram in the lateritic belt of West Bengal, India.