Bioefficacy of Pre- and Post-emergence Herbicides for Weed Control in Soybean [Glycine max (L.) Men.]

The study on bioefficacy of pre-and post-emergence herbicides for weed control in soybean at lawarharlal Nehru Krishi Vishwa Vidyalaya. Jabalpur during kharif 1995 and 1996 in barnyard grass dominated ecosystem revealed that all the pre-em. herbicides viz., clomazon 0.75 and 1.00 kg/ha, metolachlor 1.5 and 2.00 kg/ha, pendimethalin 1.5 kg/ha and alachlor 2.0 kg/ha reduced the population of Echinochloa crusgalli (L.) P. Beauv., Commelina communis L., Corchorus olitorius L. and Cyperus rolulltlus L. effectively, while the post-em. herbicides viz. sethoxydim and fluazifop-p-butyl were effective against E. crusgalli only. The highest weed control efficiency among herbicide treatments was obtained under metolachlor 2.0 kg/ha (65.5%) followed by same herbicide 1.5 kg/ha (52.8%), pendimethalin 1.5 kg/ha (42.6%) and alachlor (39%), while it varied from 27.9 to 39% under post-em, herbicides. The highest seed yield was obtained under hand weeding (913 kg/ha) closely followed by metolachlor 2.0 kg/ha (910), sethoxydim (889) and metolachlor 1.5 kg/ha (855). All the herbicide treatments were on a par to each other and hand weeding. but proved significantly superior over weedy control (542 kg/hal.