Effectiveness of integrated weed management in five varieties of aromatic rice in Bangladesh

An experiment was carried out at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, Bangladesh to evaluate the efficacy, rice selectivity and cost-effectiveness of some integrated weed control methods on the productivity of aromatic rice under randomized complete block design with three replications. The experiment consisted of five aromatic rice varieties; Kalijira, BRRI dhan34, BRRI dhan37, BRRI dhan38 and Binadhan-13, and six different weed management practices comprising no weeding, weed free, mechanical + manual weeding, pre–emergence herbicide + manual weeding, post–emergence herbicide + manual weeding, pre– + post–emergence herbicide. Ten weed species belonging to five families infested the experimental plots. Herbicide treatments provided excellent weed control efficiency and produced much higher net benefit and cost benefit ratio than weedy plot. Among the herbicidal and mechanical treatments, sequential application of Bensulfuran methyl + Acetachlor at early growth stage (pre-emergence herbicide) followed by Pyrazosulfuran ethyl at mid growth stage (post-emergence herbicide) provided the highest weed control efficiency, productivity and net benefit. Single application of Pyrazosulfuran ethyl at mid growth stage followed by one hand weeding performed very close to the pre– + post–emergence herbicide application in terms of productivity and net benefit but in terms of weed control efficiency at 45 days after transplanting application of Bensulfuran methyl + Acetachlor at early growth stage followed by one hand weeding performed very close to pre– + post–emergence herbicide application. Mechanical weeding followed by one hand weeding and application of Bensulfuran methyl + Acetachlor at early growth stage followed by one hand weeding also provided satisfactory results in terms of productivity and economic return. Since manual weeding was less economic, sequential application of pre- and post-emergence herbicides may be recommended for effective weed management in aromatic rice.