Pathogenicity of Sclerotium rolfsii on cocoyam varietes in Ghana

Abstract

The pathogenicity of five strains of Sclerotium rolfsii on four varieties of Xanthosoma mafaffa, identified as "Amankani fitaa", "Amanani fufuo", "Amankani kyirepe" and "Amankani pa" and Colocasia esculenta (Synonym Colocasia antiquorum ) in Ghana was investigated using the prescribed pathogenicity/infection tests. All cocoyam varieties were susceptible to the five strains at different rates. After 20 days of inoculation, all cocoyam plants were infected, leaves were dead and the cormls were heavily rotted. The rot progressed from top downwards. However, cormel rot was greater at the basal region than at the apical region. Strains SrXA1 and SrXA2 caused the greatest rot in wound-inoculated cornels, while infection of 3-month-old plants proceeded fastest in soils inoculated with strains SrEL1 and SrEL2. The pathogenicity was greatest on X. mafaffa var. "Amankani fitaa" and least on X. mafaffa var. "Amankani kyirepe", especially by the rotting activity of strains SrXA1 and SrEL1 and SrEL2. Considering the pathogenicity of all five strains on the cocoyam varieties tested. C. esculenta was most vulnerable to the tested S. rolfsii strains in Ghana