Virus diseases form the most important biotic production constrain of sweetpotato together with sweetpotato weevils. Single infections by most sweetpotato viruses, however, cause little to no disease in most cultivars. Mixed infections involving sweetpotato chlorotic stunt virus (SPCSV; genus Crinivirus), on the other hand, lead to severe disease complexes, causing yield losses of up to 99%. The most important among these is termed sweetpotato virus disease and caused by dual infection of SPCSV and sweetpotato feathery mottle virus (genus Potyvirus). Recent evidence suggests that it is a general property of SPCSV to be able to cause synergistic disease with co-infecting viruses, probably through suppression of host defense mechanisms. Other widespread viruses infecting sweetpotato include several potyviruses and begomoviruses as well as ipomoviruses and carlaviruses.