Integrated weed management in transplanted rice: options for addressing labor constraints and improving farmers' income in Bangladesh

In Bangladesh, weeds in transplanted rice are largely controlled by labor-intensive and costly manual weeding, resulting in inadequate and untimely weed control. Labor scarcity coupled with intensive rice production has triggered increased use of herbicides. These factors warrant a cost-effective and strategic integrated weed management (IWM) approaches. On-farm trials with transplanted rice were conducted during monsoon (‘Aman’) season in 2016 and 2017 and winter (‘Boro’) season in 2016 to 2017 in agroecological zones 11 and 12 with ten treatments – seven herbicide-based IWM options, one mechanical weed control-based option, and two checks – farmers’ current weed control practice and weed-free, to assess effects on weed control, grain yield, labor use, and profitability. Compared to farmers’ practice, herbicide-based IWM options with mefenacet+bensulfuron-methyl as preemergence (PRE) followed by (fb) either bispyribac-sodium or penoxsulam as postemergence (POST) fb one hand-weeding (HW) were most profitable alternatives, with reductions in labor requirement by 11 to 25 persons-day ha and total weed control cost by USD 44 to 94 ha, resulting in net returns increases by USD 54 to 77 ha without compromising on grain yield. In contrast, IWM options with bispyrbac-sodium or penoxsulam as POST application fb one HW reduced yields by 12 to 13% and profits by USD 71 to 190 ha. Non-chemical option with mechanical weeding fb one HW performed similarly to farmers’ practice on yield and profitability. We suggest additional research to develop feasible herbicide-free approaches to weed management in transplanted rice that can offer competitive advantages to current practices.