Clethodim for grasses control in blackgram (Vigna mungo) and its residual effect on succeeding maize (Zea mays)

A field experiment was conducted during rainy seasons of 2009–10 and 2010–11 at Guntur, Andhra Pradesh, to evaluate the bio-efficacy of clethodim against grassy weeds in blackgram {Vigna mungo (L.) Hepper} and its residual effect on succeeding maize (Zea mays L.) during winter. Post emergence application of clethodim at 96 g/ha with 0.25% non-ionic surfactant (NIS) at 20 days after sowing (DAS), significantly reduced weed growth of grasses and recorded higher crop dry weight, yield components and seed yield (0.49 t/ha) over its lower dose of 36 and 48 g/ha, but was on par with its next higher dose of 60 g/ha with 0.25% NIS + 0.04% ammonium sulphate (AMS). Clethodim did not cause any crop injury even at 96 g/ha. There was no residual effect of clethodim on succeeding maize crop. Among the clethodim treatments, post emergence application of clethodim at 96 g/ha + 0.25% NIS recorded maximum net returns (8,795/ha) and benefit:cost ratio (BCR) of 0.66 and this was closely followed by its next lower dose of 60 g/ha + 0.25% NIS + 0.04% AMS with net returns of 7,445/ha and BCR of 0.64.