Management of mixed weed flora in transplanted rice using herbicide combinations

A field experiment was conducted to study the bio-efficacy of herbicide combinations on mixed weed flora and productivity in puddled transplanted rice. Twelve treatments including bispyribac-Na 25 g/ha, penoxsulam 22.5 g/ha, bispyribac-Na 25 g + ethoxysulfuron 18.75 g/ha, tank-mix of bispyribac-Na 20 g + pre-mix of chlorimuron + metsulfuron 4 g/ha, pretilachlor 750 g followed by (fb) ethoxysulfuron 18.75 g/ha, pretilachlor 750 g fb pre-mix of chlorimuron+metsulfuron 4 g/ha, pyrazosulfuron 20 g fb pre-mix of chlorimuron + metsulfuron 4 g/ha, pre-mix of penoxsulam + cyhalofop 135 g/ha, pre-mix of triafamone + ethoxysulfuron 60 g/ha and pendimethalin 750 g at fb bispyribac-Na 25 g/ha along with hand weedings and weedy check were tested. Different herbicides recorded effective weed control and yield increase of 52–66% compared with weedy check. Unchecked weed growth depleted the soil of 234.2 kg N/ha, 17.6 kg P/ha and 292.7 kg K/ha. Sequential application of pyrazosulfuron and chlorimuron + metsulfuron (pre-mix) could not control grasses and yielded poorly compared with other herbicide combinations. Post-emergence, tank-mix application of bispyribac-Na with either ethoxysulfuron or chlorimuron + metsulfuron (pre-mix) recorded comparable yield to as obtained with sequential application of pendimethalin and bispyribac-Na or pretilachlor with either ethoxysulfuron or chlorimuron + metsulfuron (pre-mix).