Bioefficacy of Post-emergence Herbicides for Weed Controlin Soybean [Glycine max (L.) Merr.]

A field experiment was conducted during rainy seasons of 1996 and 1997 to study the bioefficacy of herbicides either alone or in combinations. Fluazifop-p-butyl at 250 g ha−1, sethoxydim at 375 g ha−1, fenoxaprop-p-ethyl at 70 g ha−1 alone controlled the most dominant Echinochloa crusgalli effectively. Commelina communis and Phyllanthus fraternus were also controlled when these herbicides were combined with lactofen at 120 g ha−1 or chlorimuron ethyl at 12 g ha−1. Fenoxaprop-p-ethyl was not compatible with chlorimuron ethyl or lactofen. Metolachlor as pre-emergence spray also reduced the weed population appreciably. The highest average seed yield was obtained under sethoxydim+chlorimuron ethyl (1240 kg ha−1) followed by sethoxydim+lactofen (1195 kg ha−1), whereas hand weeding yielded 1180 kg ha−1.