Title : pathogenic response of three cowpea varieties to infection with fusarium oxysporum f. Sp. Tracheiphylum in the screen house
Cowpea is an important legume with immense benefits to humans, animals, and the soil. Its production is threatened by many diseases among which is vascular wilt disease caused by Fusarium oxysporum f. sp. tracheiphilum (Fot). This study was carried out to evaluate three cowpea varieties commonly grown in the study area for their response to Fot infection with a view to determining their degree of tolerance/susceptibility to the disease. A 3x4 factorial experiment involving three cowpea varieties (TVU-16877, TVU-16891 and TVU-17088) and four levels of inoculation (spore/mycelia suspension, inoculum meal, spore suspension + inoculum meal and control) was conducted in the screen house. It was fitted to a completely randomized design (CRD). Data on height, number of leaves, stem girth and disease severity rating (using the CIAT DSR scale) were recorded. Analysis of variance was carried out and mean values were separated using the Tukey’s HSD at 5% level of significance. The results showed significant difference (p<0.05) in the growth parameters for the different cowpea varieties. Variety TVU-16891 was the most severely affected having the lowest mean number of leaves (at 8 and 10 WAP) and the smallest mean stem girth (at 4, 6, 8 and 10 WAP). Disease severity rating was significantly affected by the inoculation methods and the interaction between inoculation methods and varieties. This study also revealed that variety TVU-17088 was tolerant/resistant to spore/mycelia suspension + inoculum meal inoculation (to which the other cowpea varieties were susceptible) and showed intermediate response to the other two inoculation methods. The study shows how the three cowpea varieties responded to infection by the pathogen and their classification based on the disease severity rating.