Performance of different herbicide combinations for weed management in transplanted rice

Abstract:

Here is a surprising fact: weeds cause higher yield losses in Nigerian rice than any insect or disease, yet most smallholders in Benue State still rely on one or two hand weedings that arrive too late to prevent the critical first-flush competition. This research compared six herbicide combinations and two manual weeding controls for weed management in transplanted rice variety FARO 44 during the 2023 wet season at Niger-Benue Agricultural University, Makurdi, Nigeria. Pendimethalin 30 EC (1.0 kg a.i./ha) applied pre-emergence followed by bispyribac-sodium 10 SC (25 g a.i./ha) at 25 DAT achieved the highest weed control efficiency of 91.8% and grain yield of 4.87 t/ha, representing a 127.6% increase over the weedy check (2.14 t/ha). Two hand weedings at 20 and 40 DAT gave 87.4% WCE and 4.62 t/ha but cost 3.4 times more labour than the herbicide combination. Pendimethalin alone controlled grasses adequately but missed sedges, underscoring the value of sequential tank-mix strategies. The pendimethalin + bispyribac combination is recommended as the most cost-effective weed management option for transplanted rice in Nigeria's middle belt.