Synchytrium endobioticum
AKA: black scab
Potato wart disease is present in: Africa: South Africa, Tunisia. Asia: Armenia, Bhutan, China, India, Nepal; Europe: Armenia, Belarus, Bulgaria, Czech Republic, Denmark, Estonia, Faroe Islands, Finland, Georgia, Germany, Greece, Ireland, Italy, Luxembourg, Montenegro, Netherlands, Norway, Poland, Romania, Russia, Slovakia, Sweden, Turkey, Ukraine, United Kingdom; North America: Canada (Newfoundland, Prince Edward Island); Oceania: New Zealand; South America: Bolivia, Falkland Islands, Peru.
Potato is the only known cultivated host that can be infected by Synchytrium endobioticum, the chytrid fungus that causes potato wart disease. S. endobioticum also infects several other wild hosts in the genus Solanum.
Evidence of potato wart disease may be seen on all underground plant parts except the roots. "Warts" or roughly corrugated branched galls are formed primarily on the stems, tubers, and stolons. The galls feel soft and can vary in size from as small as 1 cm in diameter to growths larger than the tuber from which it emerges. The galls initially present white in color if underground or green for galls above the soil line, but all galls will eventually darken upon decay.
