Efficacy of pre-and post-emergence herbicides with and without weeding in forage cowpea (Vigna unguiculata)

A field experiment was conducted at Forage Research and Management Centre of the National Dairy Research Institute, Karnal, Haryana during the rainy season (kharif) of 2014 on sandy clay loam soils, to find out cost-effective weed-control method in forage cowpea [Vigna unguiculata (L.) Walp.]. Application of pendimethalin 1.0 kg/ha as pre-emergence followed by 1 hand-weeding (HW) 40 days after sowing (DAS) resulted in the lowest weed density, weed dry matter and the highest weed control efficiency, herbicide efficiency index and weed-management index and was followed by imazethapyr 0.075 kg/ha followed by hand-weeding (HW) at 40 DAS due to the efficient control of dominant weed Trianthema monogyna. Uncontrolled weeds reduced the seed yield by 43% compared to weed-free treatment. Pendimethalin @ 1.0 kg a.i./ha + 1 HW at 40 DAS recorded maximum seed yield, net returns and benefit: cost ratio.