PATHOGENICITY OF RENIFORM NEMATODE (ROTYLENCHULUS RENIFORMIS, LINFORD AND OLIVEIRA, 1960) ON COWPEA (VIGNA UNGUICULATA)

– Studies on the pathogenicity of reniform nematode (Rotylenchulus reniformis Linford & Oliveira, 1940) on cowpea (Vigna unguiculata) under greenhouse conditions showed that there was a progressive decrease in the plant growth parameters as the inoculum level of Rotylenchulus reniformis increased, i.e., 10, 100, 500, 1000, 5000, and 10,000 nematodes per pot (1kg). An initial inoculum level of 1000 nematodes per kg of soil caused a significant reduction in shoot length, root length, shoot and root weight and proved to be pathogenic to cowpea (var. local). With an increase in the inoculum level, there was a gradual increase in the number of females, egg masses per root system, and nematode population of Rotylenchulus reniformis in 1 kg of soil. The reproductive rates were found to be inversely proportional with inoculum levels, with the highest at 100 and the lowest at 10,000 nematodes per pot. Based on these results, it can be concluded that the threshold level of reniform nematode, Rotylenchulus reniformis was 1000 nematodes per kg of soil.