Bio-efficacy of herbicides on weeds in direct-seeded rice in Konkan region of India

Rice cultivation by direct seeding is viewed as both cost and labor-saving practice and becoming popular alter- native to transplanting. Weeds are a more serious problem in DSR than in transplanted rice. The field experimen- tal is conducted to evaluate the bio -efficacy of pre and post – emergence herbicides, hand-weeding on weed con- trol, yield components, yield and their economic feasibility for cost effective weed control in direct seeded rice. The experiment was laid out in randomized block design with three replications and seven treatments, viz. Pre-emer- gence oxadiargyl 80% WP @ 100 g/ha, Pre-emergence oxadiargyl 80% WP @ 100 g/ha fb HW at 30 DAS, oxadiargyl 80% WP (PE) @ 100 g/ha fb Post-emergence bispyribac- Na @ 25 g/ha at 25 DAS, Pre-emergence oxadiargyl 80% WP @ 100 g/ha fb Post-emergence metasulfuron- methyl + chlorimuron – ethyl @ 4 g/ha at 25 DAS, Pre-emergence oxadiargyl 80% WP @ 100 g/ha fb Post-emergence carfentrazone ethyl 40% @ 25 g/ha at 25 DAS. Weed density under weedy check (WC) situation showed that monocot weeds (grasses and sedges) were more pre-dominant wherein grasses and sedges constituted 74.80% and 11.48%, respectively, BLWs 14.20% of total weed density at 60 DAS of crop. Amongst the herbicide treatments, application of Oxadiargyl (PE) @ 100 g/ha fb HW at 30 DAS recorded significantly lowest number of weeds/m2, dry weight/m2. The highest grain yield (4.02 t/ha) and benefit cost (1.48) were recorded with the pre-emergence application of Oxadiargyl (PE) @ 100 g/ha fb HW at 30 DAS.