Pathogenic Responses of Cowpea (Vigna unguiculata) Inoculated with Cucumber Mosaic Virus to Soil Amendment with Neem Leaf Powder

Abstract

A study was carried out using potted plants arranged in a randomized complete block experimental design, to evaluate the pathogenic responses of Cowpea that was inoculated with cucumber mosaic virus to soil amendment with neem leaf powder. The amendments were applied at varying rates of 0.125Kg/10kg soil, 0.25Kg/10Kg soil and 0.5Kg/10Kg soil, and at the time of two weeks before planting, at planting and at two weeks after planting. Plants that served as control were also inoculated with the virus but were sown in soil not amended with neem leaf powder. Results from the experiment indicated that amendment of the soil with neem-leaf powder produced plants that were less vulnerable to diseases occasioned by viruses. The rate and time of the application of the neem leaf powder also appeared to be an important factor in this regard. It was observed that application of relatively lower rate of 0.125kg neem leaf powder per 10kg of soil at two weeks prior planting conferred the highest tolerance to virus diseases, as these treatment plants had the highest growth indices and yields. On the other hand, plants grown in soil amended at the higher rate of 0.50kg neem leaf powder per 10kg of soil two weeks after planting, had the lowest growth and yield attributes which were similar to the control. This experiment suggests that neem leaf powder applied as soil amendment at an appropriate rate and time could achieve possible potentials for virus disease control in cowpea.

Keywords: Neem leaf powder, Rate and Time of Application, Inoculation, Cucumber mosaic virus, Cowpea, Soil amendment.