SCREENING COWPEA (Vigna unguiculata (L.) Walpers) LINES FOR RESISTANCE TO SOME VIRUSES IN NIGERIA

Thirty-three Cowpea lines were screened in a greenhouse at Ibadan, southwest Nigeria for response to four cowpea viruses, namely the bean common mosaic Potyvirus-blackeye Cowpea strain (BCMV-BIC), Cowpea aphid-borne mosaic Potyvirus (CABMV), Cowpea Mottle Carmovirus (CMeV) and southern bean mosaic Sobevirus (SBMV). Disease severity was scored from; 1=no infection, to 5=very severe infection. Symptomless lines were serologically tested with protein-A sandwich enzyme- linked immunosorbent assay (PAS-ELISA) to distinguish lines with latent infection from the non-infected lines. Nine Cowpea lines were severely or very severely infected by the four viruses. Three viruses namely BCMV-BIC, CABMV and SBMV-BIC did not infect two lines (IT90K-284-2 and IT82D-889). In addition, CABMV and BCMV-BIC did not infect the cowpea varieties IT85F-2687 and Futo Coiled. SBMV and BCMV-BIC did not cause infection on CP-VAR8. No infection in some Cowpea lines indicated resistance to the virus and such lines are potential breeding materials for elite varieties. The incidence of BCMV-BIC infection was 100% in 13 lines, CABMV infection in 9, CMeV in 15 and SBMV in 3