Indian Journal of Weed Science

The efficacy of herbicide combinations on weed control in wet-seeded rice with grasses as dominant weed flora was evaluated in field experiments conducted at Kerala Agricultural University, India during 2018 and 2019. Experiment comprised of 10 treatments, viz. cyhalofop-butyl (CB) 80 g/ha, penoxsulam (PS) + cyhalofop-butyl (6% OD) – commercial formulation 150 g/ha, cyhalofop-butyl 80 g/ha + carfentrazone-ethyl (CE) 200 g/ha, bispyribac-sodium (BS) 25 g/ha, bispyribac-sodium 25 g/ha + cyhalofop-butyl 80 g/ha, bispyribac-sodium 25 g/ha + fenoxaprop-p-ethyl (FPE) 60 g/ha, fenoxaprop-p-ethyl 60 g/ha, stale seedbed (SSB) fb chemical weeding with glyphosate 800 g/ha + oxyfluorfen 150 g/ha at 15-20 days after land preparation + cyhalofop-butyl 80 g/ha + carfentrazone-ethyl 200 g/ha, hand weeding twice at 20 and 45 DAS and unweeded control (UWC). The population of grass weeds increased over time, occupying 48.9 and 42.3% of the weed spectra during the initial phase and peaking at 87.40 and 75% towards 60 DAS, respectively during 2018 and 2019. Tank mix application of bispyribac-sodium 25 g/ha + fenoxaprop-p-ethyl 60 g/ha resulted in the lowest density of grass weeds at all stages and registered 100 and 92.97% reduction in weed count over unweeded control at 15 and 45 days after treatment application, respectively. The tank mix of bispyribac-sodium with cyhalofop-butyl and fenoxaprop-p-ethyl improved weed control compared to their individual application. Post-emergence herbicide combinations of bispyribac-sodium + fenoxaprop-p-ethyl, penoxsulam + cyhalofop-butyl (6% OD) and bispyribac-sodium + cyhalofop-butyl registered superior weed control efficiency than the broad-spectrum herbicide bispyribac-sodium and increased the grain yield by 58.84, 56.78, and 56.51 %, respectively over the unweeded control.