Résumé
Among the 25 viruses recognized officially in yams (Dioscorea spp.) worldwide, nine have been reported in yams in Guadeloupe. Since the epidemiology of these viruses remains largely unexplored, we undertook a large-scale epidemiological study of yam viruses in Guadeloupe based on the analysis of 1124 leaf samples collected from yams and weeds. We assessed the prevalence of cucumber mosaic virus (CMV), Cordyline virus 1 (CoV1), Dioscorea mosaic associated virus (DMaV), yam asymptomatic virus 1 (YaV1), yam mosaic virus (YMV), yam mild mosaic virus (YMMV), badnaviruses, macluraviruses and potexviruses, and evaluated the effects of key epidemiological drivers of these viruses.We identified several weed reservoirs of YMMV and provide evidence that YMMV isolates infecting weeds cluster together with those infecting yams, pointing to the role of weeds in the epidemiology of YMMV. We report on the occurrence of yam chlorotic necrosis virus (YCNV) in Guadeloupe, the introduction of YMMV isolates through the importation of yam tubers, and the absence of vertical transmission of YaV1. We identified specific effects of some cropping practices, such as weed management and the use of chemical pesticides, on the occurrence of several yam viruses, but no crop-related factor had a strong or general effect on the overall epidemiology of the targeted viruses. Overall, our work provides insights into the epidemiology of yam viruses that will help design more efficient control strategies.