EFFECTS OF SWEET-POTATO VIRUS-DISEASE (SPVD) ON THE YIELD OF SWEET-POTATO GENOTYPES IN CAMEROON

Sweet potato virus disease (SPVD) causes strap-shaped leaves, vein-clearing, puckering, chlorosis and stunting in susceptible sweet potato varieties and yields are much reduced. To investigate the tolerance of genotypes and obtain a better appraisal of yield loss caused by SPVD, eight sweet potato varieties showing symptoms of SPVD were studied for two years in an area where SPVD is severe. Two varieties, although showing symptoms, were tolerant of the disease; their yields were not significantly depressed by SPVD. Among the remaining six varieties, storage root fresh yields were reduced by 56-90% in plants showing SPVD symptoms. Marketable yields, as well as total and marketable numbers of storage roots were similarly depressed by SPVD in the less tolerant varieties. Significant correlations were found between disease severity rating and yield reduction among cultivars.