Weed control in soybean (Glycine max (L.) Merrill) using acifluorfen and bentazon herbicides in North-central zone, Nigeria

The influence of acifluorfen and bentazon in the control of weeds in soybean was studied at the Students’ Research and Demonstration Farm, Kogi State University, Anyigba during the 2016 growing season. A low shattering and early maturity soybean cultivar with high oil content, TGX 1830-20E was used in this trial. The two herbicides were applied post-emergence at two rates each. Acifluorfen (5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoic acid) was applied at 0.2 and 0.4 kg a.i/ha;bentazon (3-(1-methylethyl(-(1H) -2, 1, 3 –benzothiadazin -4(3H) –one  2,2 – dioxide ) at 0.5 and 1.0 kg a.i/ha, while their mixtures, acifluorfen + asulam applied at 1.3 and 1.6 kg a.i /ha and bentazon + asulam at 1.4 and 1.7 kg a.i/ha. Parameters measured included phytotoxicity of the herbicides to soybean, weed control effectiveness, plant height, number of pods/plant, number of seeds/plant, seed weight /plant and total grain yield (kg/ha). Results showed that weed control effectiveness was higher and the crop performance most especially in terms of total grain yield (Kg/ha) was better in plots that received mixture formulation of acifluorfen + asulam and bentazon + asulam than where acifluorfen or bentazon was applied as single formulation irrespective of rates. The highest grain yield (1066 kg/ha) obtained from plots to which 1.6 kg a.i/ha of acifluorfen + asulam was applied compared favourably with that realized from the hoe weeded plots (1044.5 kg a.i/ha). Abysmally low grain yield was obtained from the weedy check.