Assessment of Yield Loss of Cowpea (Vigna unguiculata L.) due to Root Knot Nematode, Meloidogyne incognita under Field Conditions

The root knot nematodes are included within the genus Meloidogyne Goldi, 1892 and belong to a relatively small but important polyphagous group of highly adapted obligate plant pathogens. Typically, they are distributed worldwide and parasitize nearly every species of higher plant. Due to their endoparasitic way of living and feeding, root knot nematodes disrupt the physiology of the plant and may reduce crop yield and product quality and, therefore, are of great economic importance and make control necessary. Field studies were conducted in 2008 and 2009 to determine yield loss of cowpea (cv. ART98-12) due to natural infestation by M. incognita using Carbofuran 3G at 2kg a.i./ha and untreated as check. The yield of cowpea was found to be higher with the application of nematicide-Carbofuran 3G at 2kg a.i. /ha. The percentage increase over control was 39.0 and 33.0% in the years 2008 and 2009, respectively. A significant reduction in the yield of cowpea in untreated plots was mainly attributed to direct damage of the root system by the feeding of root-knot nematode, M. incognita. The root knot nematode population in carbofuran treated plots was significantly lower than in check in the two years, also at harvest. In the check the nematodes reproduced many folds during the cropping season. Higher nematode population in the untreated check decreased plant growth and consequently reduced the number of harvested seeds and other agronomic parameters.