Assessment of Herbicide Efficacy for Weed Management in Soybean in Benue State

This study assesses the efficacy of different herbicide treatments for weed management in soybean production in Benue State, North Central Nigeria. Soybean is an important protein and oil crop in Benue State, but weed competition significantly limits yield potential, particularly during the first six weeks of crop growth. Herbicide-based weed management offers potential for reducing the high labour costs of hand weeding, but the effectiveness of available herbicide products under Benue State weed community conditions has not been comprehensively evaluated. This study establishes a randomised complete block design experiment at the University of Agriculture Makurdi, testing six herbicide treatments: pre-emergence pendimethalin, pre-emergence metalachlor, post-emergence bentazon, post-emergence fomesafen, sequential pre-emergence pendimethalin followed by post-emergence bentazon, and two hand weedings as the standard reference. Weed control efficiency, weed dry weight, soybean canopy development, and grain yield are assessed over two growing seasons using TGX1835-10E variety. Findings reveal that the sequential herbicide treatment achieves weed control efficiency of 92 percent and soybean grain yield of 2.6 tonnes per hectare, statistically equivalent to two hand weedings at 2.7 tonnes per hectare and superior to all single herbicide treatments. Post-emergence bentazon alone is most effective against broadleaf weeds but leaves grasses poorly controlled. The study concludes that sequential herbicide application provides the most comprehensive weed management for soybean in Benue State. It recommends this approach for extension guidance where herbicide access is available.

Keywords: herbicide efficacy, soybean weed management, Benue State, weed control, sequential application.