SEVERITY OF INFECTION OF THREE UNRELATED VIRUSES ON COWPEA CUL TIVARS

Abstract

A study was conducted to determine the severity of three unrelated viruses; Cowpea aphid-borne mosaic virus (CABMV), Cowpea mottle virus (CMeV), and IBean southern mosaic virus (SBMV) on symptoms induced in three cowpea cultivars, "OLO II", "OLOYIN", and IT86D-719. The rating done on a scale of 0-5 with respect to symptomatology indicated that the viruses have significant (P=0.05) severe effects on the virus inoculated plants compared to the control. The age of plants at the time of inoculation also have drastic effect on the symptoms

induced on plants. Inoculations of plants at early age of 10 days after planting (DAP) resulted in more severe symptoms than inoculations at later age of 30 DAP. More so as the days of observation increased from 10 days after inoculation (DAI) to 30 DAI, the severity of infection also increased. The severity of the viruses on symptom rating of cultivars indicated that CABMY induced the greatest effects in IT86D-719 at 10 DAP with ratings of 3,4 and 5 at

10,20 and 30 DAI respectively; CMeV had the highest severity on "OLOYIN" while SBMV caused more severe effects in "OLO II" which rated 4, 4, and 5 at 10, 20 and 30 DAI respectively for plants inoculated at 10 DAP.