Weed management by herbicide combinations in transplanted rice

Field experiments were conducted in transplanted rice at Visva-Bharati, Sriniketan during Kharif seasons of 2012 and 2013. The predominant weed species were: Ludwigia parviflora, Cyanotis axillaris, Commelina diffusa and Spilanthes acmella. Pre-emergence application of pretilachlor + bensulfuron at 660 g/ha and post-emergence application of bispyribac-sodium + metsulfuron-methyl + chlorimuron- ethyl at 4 g/ha effectively controlled grassy weed population. Post-emergence application of bispyribac + metsulfuron-methyl + chlorimuron-ethyl was found to be most effective in controlling broad-leaved weeds and it was closely fb bispyribac + ethoxysulfuron applied as post-emergence. Application of bispyribac-sodium + metsulfuron-methyl + chlorimuron-ethyl as post-emergence and pyrazosulfuron- ethyl as pre-emergence were effective in controlling sedge population. Post-emergence application of bispyribac + ethoxysulfuron, pretilachlor fb metsulfuron-methyl + chlorimuron-ethyl, pyrazosulfuron fb manual weeding, pretilachlor + bensulfuron and weed-free check recorded more grain yield. The highest net returns and B:C ratio were recorded with bispyribac + metsulfuron-methyl + chlorimuron-ethyl and pre-emergence application of pretilachlor fb metsulfuron-methyl + chlorimuron-ethyl. Herbicides applied in combination recorded more net returns and B:C ratio as compared to sole application of herbicides.