Tubers, stolons and occasionally leaf stalks affected, but not roots. Tubers may bear cauliflower-like tumours at the eyes or whole tuber may become shapeless warted mass. May progress in store even from minute warts not seen at lifting.
Organism in soil, may remain infective for more than 30 years. Spread on implements and in dung from stock fed with infected tubers. More severe in wet seasons.
Varietal: Most varieties are immune. Non-immune varieties include Bintje, Duke of York, Kennebec, King Edward, Morene, Royal Kidney, Sharpes Express and Up-to-Date.
Cultural: Notifiable disease. Potatoes prohibited from infected land until disease no longer present. All classified seed must be grown on land free from wart disease.
Chemical: Not permitted.