Performance of herbicides for managing weed flora in transplanted aman paddy (Oryza sativa L.)

A field investigation was performed during the rainy seasons of 2018 and 2019 at the Instructional Farm, Bidhan Chandra Krishi Viswavidyalaya, Jaguli, Nadia, West Bengal, India (22056'N and 86048'E, 9.75m above mean sea level) with the aim of determining the comparative effectiveness of different herbicides in controlling various kinds of weeds (grass, sedge and broad-leaf) in the transplanted aman paddy. The experiment was laid out in Randomized Block Design having sixteen treatments with three replication, that includes application of either pre-emergence [butachlor, pretilachlor, pyrazosulfuron ethyl and ready mix (RM) of bensulfuron methyl + pretilachlor at 2 days after transplanting (DAT)] or post-emergence [bispyribac sodium and bispyribac sodium + penoxsulum at 20 DAT] herbicides followed by hand weeding at 40 DAT; application of both pre-emergence and post-emergence herbicides; hand weeding at 20  and 40 DAT and weedy check. Hand weeding at 20 and 40 DAT registered significantly lower weed density, weed dry matter and the highest weed control efficiency. Among the herbicidal treatments, ready-mix formulation of bensulfuron methyl 0.6% + pretilachlor 6% (Londax power 6.6%) performed better in controlling weeds of all categories and recorded higher paddy (3.96 t/ha)  and straw yield (4.92 t/ha ) with the maximum weed index which were statistically at par with the hand weeded treatment. Hence, to fetch the effective suppression of weed, application of Londax power 6.6% @ 0.66 kg a.i./ha as pre-emergence (at 2 DAT) with hand weeding at 40 DAT can easily replace additional one hand weeding at 20 DAT.