International plant virus epidemiology workshop : resistance to viruses and vectors, temperate and tropical plants

Yam mosaic virus (YMV), a member of the Potyvirus group, causes a severe disease of yam, #Dioscorea$ spp., mainly in Africa and the Carribean. There have been no data available hitherto on the quantitative effects of the disease on crop yield, due to difficulties in detecting the presence of the virus in plant. By using ELISA tests to identify healthy yam material prior to and after planting, reliable estimates of crop losses due to YMV were obtained through serial field trials over a three years period. Fresh tuber weights obtained from diseased #Dioscorea alata$, cv. Florido averaged 15% lower than those obtained from healthy plants grown under similar conditions. There was no difference however in the number of tubers formed. Disease contamination by aphid vection during crop growth was found to be relatively slight compared to disease levels in the initial seed tubers. This suggests that selection of virus-free tubers could rapidly eradicate yam mosaic disease. (Résumé d'auteur