Aetiology and ecology of a yam mosaic disease in Burkina Faso

Abstract

Yam virus diseases were surveyed for 3 years in Burkino Faso. Mosaic and green vein banding symptoms were observed on two species (#Dioscorea cayenensis rotundata and #Dioscorea alata) in the south-west and southern aeras, and on the Pilimpikou yam cultivar in the central area. Using electron microscopy, ELISA and host range studies, it was found that plants were infected with a potyvirus similar to yam mosaic virus in host range, morphology and serology. This virus was not detected in the southern area but occurred at a low rate (13%) in the south-west and more frequently (71.5%) in the central aera. Healthy yam plants were exposed to natural infection for 5 months in these two areas and checked for virus contamination by ELISA. Tubers from markets were also checked. During crop growth, in natural conditions, disease contamination was relatively slight compared with that in tubers from markets. The reliability of virus detection methods is discussed. (Résumé d'auteur