Bio-efficacy of herbicides in direct-seeded rice

A field study was conducted during summer seasons of 2015 and 2016 to evaluate the efficacy of post-emergence herbicides at Navsari Agricultural University, Navsari. Total twelve treatments consisting of pretilachlor 1250 g/ha and pyrazosulfuron-ethyl 25 g/ha as pre-emergence (PE); bispyribac-sodium salt 50 g/ha and cyhalofop-butyl 100 g/ha at 20 DAS as post-emergence; stale seedbed, hand weeding and unweeded check were evaluated. Pretilachlor 1250 g/ha PE or pyrazosulfuron-ethyl 25 g/ha fb bispyribac-sodium salt 50 g/ha at 30 DAS suppressed both weed density and dry weight over control. Growth and yield attributes, viz. plant height, no. of tillers, no. of panicles/length of panicles and no. of grain/panicles were improved significantly with pretilachlor 1250 g/ha PE fb bispyribac-sodium salt 50 g/ha at 30 DAS and pyrazosulfuron-ethyl 25 g/ha fb bispyribac-sodium salt 50 g/ha at 30 DAS. Similarly, higher rice grain and straw yields and maximum net returns were also associated with these combinations. Pre-and post-emergence application of pretilachlor 1250 g/ha or pyrazosulfuron-ethyl 25 g/ha PE fb bispyribac-sodium salt 50 g/ha at 30 DAS appeared to be a viable strategy for weed control in direct-seeded rice with higher economic returns.