Weed Management in Cowpea through Combined Application of Allelopathic Sorghum Residues and Less Herbicide

Abstract

—A Field study was conducted to explore the allelopathic potential of sorghum residues alone and in combination with half (1.2 L ha-1) of recommended rate of trifluralin herbicide for controlling weeds in cowpea field. Sorghum residues at 5 and 10 t ha-1 were used either alone or in combination with trifluralin at 1.2 L ha-1. Trifluralin at full label rate (2.4 L ha-1), weedy check and weed free treatments were also included for comparison. Incorporation of sorghum residues at 5 and 10 t ha-1 reduced weed density by 6 and 43 % of control and dry weight biomass by 48 and 66% of control, respectively. However, application of herbicide at 50% rate in plots amended with sorghum residues at 5 and 10 t ha-1 provided weed density and dry weight biomass suppression greater than that of full herbicide rate treatment. Chemical analysis of sorghum residues amended field soil revealed the presence of phenolics in higher concentration. Periodic data revealed that maximum quantities of phenolics were coincided with the period in which maximum suppressive activity against the weeds was noticed. Application of sorghum residue at 10 t ha -1 to the plots amended with half rate of trifluralin herbicide provided seed yield significantly higher than that achieved by sole application of label rate of herbicide, which could be used as a feasible and environmentally sound weed management approach in cowpea field.