Studies on Some Physiological Characteristics and Pathogenicity of Sclerotium Rolfsll Sacco Causing Collar Rot and Cormel Rot of Cocoyams (Coloca.Sia and Xanthosoma Species) in Ghana.

Abstract

The physiological and morphological characteristics of five strains of Sclerotium rolfsii, namely, XLL, XAl, XA2, ELI and EL2, which were identified as strains by the aversion test, were studied. The susceptibility of five varieties of cocoyam, 'Amankani fitaa', 'Arnankani fufuo', 'Arnankani kyirepe' and 'Amankani pa' of Xanthosoma sagittifolium and a single variety of Colocasia antiquo rum to these strains, was also investigated. The appearance of the strains on Potato Dextrose Agar plates was similar and mycelial dry weights in Potato Dextrose Broth after 6 days' incubation were statistically similar. However, extensional growth on PDA was fastest in Strains ELI and EL2, moderate in Strains XLL and XAI and slowest in Strain XA2. Cultures of Strain XLL produced a mean number of 185 larger and heavier sclerotia per Petri plate whereas the remaining four strains formed 324 to 364 smaller and lighter sclerotia per Petri plate.