Assessment of the Efficacy of Leave Extracts of Some Botanicals Against Black Pod Disease of Cocoa (Theobroma Cacao. L)
This study assessed the efficacy of Chromolaenaodorata, Acalyphawilkesiana, Tithoniadiversifolia, and Vernoniaamygdalinacrude leaves extracts for black pod disease of cocoa (Theobroma cacao L.) control.Phytophthoramegakarya was isolated from cocoa pods with symptoms of black pod disease, identified and the pathogenicity of the disease was established. Aqueous and N-hexane extracts of Chromolaenaodorata, Acalyphawilkesiana, Tithoniadiversifolia, and Vernoniaamygdalina, and Ultimax fungicide (used as the standard for comparison) were prepared and tested against the fungal pathogen at 30, 50, 70, and 100% concentration respectively, poison food technique. Agar plates without extract/fungicide served as the control. Aqueous N-Hexane extracts of the medicinal plants, exhibited significant inhibitory effects on the radial mycelial growth of the fungal pathogen at the tested concentrations, and Vernoniaamygdalina extracts were most effective against the fungal pathogen at 30% N-Hexane extract, 80.78% inhibition and 100% aqueous 71.06%. Vernoniaamygadalina extract competed favourably with the standard (Ultimax fungicide) in the mycelial inhibition of P.megakarya. Vernoniaamygadalina was most effective against for cocoablack pod disease and can substitute harmful synthetic agrochemicals.
Keywords- P. megakarya, Cocoa, Botanical extracts, Fungicides, Black pod disease