Management of Bean common mosaic virus strain blackeye cowpea mosaic (BCMV-BlCM) in cowpea using plant extracts

Abstract

Efficacy of certain plant extracts in reducing Bean common mosaic potyvirus strain blackeye cowpea mosaic (BCMV-BlCM) disease in cowpea was evaluated. All the six botanicals Azadirachta indica, Boerhaavia diffusa, Bougainvillea spectabilis, Clerodendrum inerme, Psidium guajava, and Thuja occidentalis improved the germination and vigour index of cowpea. The disease incidence was reduced to 7% when 0.75% (w/v) of B. diffusa leaf extract was used as seed treatment under screen house conditions when compared to 80% in control. Under field conditions B. diffusa reduced the disease incidence up to 40% at 0.75% (w/v) concentration of extract. In spray treatment, B. diffusa and B. spectabilis reduced the disease incidence up to 13 and 12% under screenhouse conditions, whereas B. diffusa and C. inerme reduced the disease incidence up to 31 and 32% under field conditions. When plant extracts were mixed with BCMV-BlCM inoculum and young seedlings inoculated, B. spectabilis, C. inerme and M. jalapa extracts reduced the disease incidence up to 42, 40 and 48% respectively under screenhouse conditions when compared with the control.