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.