Pretilachlor + pyrazosulfuron-ethyl (ready-mix) against complex weed flora in transplanted rice and its residual effects

A field experiment was conducted at CCS HAU, Regional Research Station, Kamal during Kharif 2010 to 2014 to evaluate the bio-efficacy of pretilachlor 6.0% + pyrazosulfuron-ethyl 0.15% GR (ready-mix) against complex weed flora in transplanted rice and also to study its residual effects. Results from on-station experiment (2010 and 2011) revealed that the optimum dose of pretilachlor + pyrazosulfuron-ethyl was 615 g/ha which provided effective control (91–96%) of complex weed flora in transplanted rice, with higher grain yield (5.98–6.05 t/ha) and B-C ratio (2.19–2.28). In general, it was comparable to its higher doses, bensulfuron-methyl + pretilachlor 660 g/ha, pretilachlor 1000 g/ha, butachlor 1500 g/ha, bispyribac-sodium 25 g/ha and weed free check in terms of weed control, grain yield of rice and benefit-cost ratio. In comparison to weedy check, there was 54–57% increase in grain yield of transplanted rice under pretilachlor + pyrazosulfuron-ethyl 615 g/ha. On an average of 19 adaptive/farmers-participatory trials, pretilachlor + pyrazosulfuron-ethyl 615 g/ha proved superior to commonly used herbicides butachlor 1500 g/ha in 2013 and pretilachlor 1000 g/ha in 2014 in terms of weed control and grain yield of rice. There was no phyto-toxicity of pretilachlor + pyrazosulfuron-ethyl on transplanted rice up to 1230 g/ha (2x dose) and it was also safe to the succeeding chickpea and wheat (2011–12, 2012–13 and 2012–13) crops in rotation.