Response of soybean [Glycine max (L.) Merrill] and associated weeds to pre-emergence application of chlorimuron ethyl and metolachlor.

Afield study conducted during kharif season for two years on medium black soils revealed that chlorimuron ethyl @ 9 and 12 g/ha as pre-emergence (PE) applied 3 DAS reduced the population ofCyperus rotundus L. significantly over its lower dose of 6 g/ha and weedy control plot. Whereas grassy and dicot weeds were not controlled even with higher rates. Metolachlor application@ 2.0 kg/ha as PE suppressed C. rotundus significantly compared with weedy control plot. Similarly, grasses were controlled effectively than that of chlorimuron ethyl but it was ineffective on dicot weeds. Total number of weeds was reduced significantly under metolachlor treated plots as compared to chlorirnuron ethyl. Although metolachlor was superior to chlorirnuron ethyl in reducing total dry weed biomass production at harvest but it was inferior to two hand weedings (HW) at 20 and 35 DA8. As far as growth and yield parameters and grain yield are concerned, application of dllorimuron ethyl at any rate was not effective and produced only 32.9–35.8% more grain yield over weedy control. On the other hand, metolachlor improved all growth as well as yield parameters resulting in significantly higher grain yield of 2060 kg/ha (54.54%) higher over weedy control plot which was comparable with two manual weedings (2160 kg/ha).