Comparative Evaluation of Hoe-weeding and Pendimethalin Spray Regimes on Weed Management in Cowpea (Vigna unguiculata (L) Walp.) in North Central Nigeria

Field trials were conducted at the Teaching and Research farm of Landmark University Omu-Aran during the cropping seasons of 2013 and 2014 to test the best time of Pendimethalin application in comparison with hoe weeding on weed management and performance of cowpea (Vigna unguiculata (L) Walp.). The treatments were the weed management practices: Hoe weeding at 3 and 6 weeks after planting (WAP); Pre-plant Pendimethalin (3 days before planting, DBP); Pendimethalin at Planting; Post-plant Pendimethalin (2 days after planting, DAP) and weedy check control. Obtained results showed that Pendimethalin, irrespective of time of application showed no significant germination percentage reduction in comparison with the control or hoe weeding. All the Pendimethalin sprayed plots gave effective weed biomass reduction similar to those obtained from the hoe weeded plots. Higher yield factors in terms of number of leaves, number of branches, plant height, and pod weight per plant were consistently similar and highest in the Pendimethalin and hoe weeded plots. Irrespective of time of Pendimethalin application, similar values of number of pods per plant, pod length and number of grains per plot were obtained with hoe weeded plots which were higher than the control. Lower pod weight and grain yields were obtained in Pendimethalin at planting when compared with the pre-plant, post-plant Pendimethalin and hoe weeding which recorded the highest pod and grain yields. Establishment rate showed that Pendimethalin applied at planting and post-plant resulted into lower field seedlings count at 4WAP. It is concluded that Pendimethalin applied three days before planting gave effective weed control and produced the highest cowpea grain yield in the study area.