Evaluation of bensulfuron-methyl for weed control in wet direct-sown summer rice

摘要

The efficacy of bensulfuron-methyl alone or as tank mixture with pretilachlor was evaluated in conjunction with recommended herbicides pretilachlor and pyrazosulfuron-ethyl for controlling sedges and broad leaf weeds in wet direct- sown summer rice during the dry season of2006 and 2007 at Cuttack. The major weed flora constituting in weedy plots were Echinochloa colona (8.7%), Cyperus difformis (26.1%), Fimbristylis miliacea (14.5%), Sphenochlea zeylanica (27.5%)) and Marsilea quadrifolia (23.2%)) at30 days after soMng (DAS). Bensulfuron-methyl either alone at 60 g ha' or as tank mixture with pretilachlor (50+450 g ha~(-1)) applied at 20 DAS were found to be equally effective in controlling weeds (weed control efficiency 90.0 and 92.2%, respectively) and produced comparable grain yield of 5.48 and 5.53 t ha~(-1), respectively. Both these herbicide treatments were at par with recommended practice of hand weeding twice at 20 and 40 DAS in terms of weed control efficiency (WCE) and grain yield. Bensulfuron-methyl at 30 to 60 g ha' applied alone or as tank mixture with pretilachlor at 450 g ha~(-1) was found superior in reducing the total weed density and dry matter production with WCE of 80-92.2% in comparison to the recommended herbicides pretilachlor and pyrazosulfuron-ethyl with WCE of 74 and 75.8% respectively. There was more than 49% reduction in the grain yield of rice due to competition with weeds in weedy plots.