If the disease were to reappear, it could be devastating to the U.S. potato industry because of potential losses in production and export markets. In addition, the spores of the fungus can remain viable in contaminated soil for many years. Potato wart is primarily a soil-borne disease. On infected tubers, the eyes develop into characteristic warty, cauliflower-like swellings. When formed underground, they are the same color as the potato skin, but gradually darken with age.
Diseased potatoes are deformed and unmarketable.
Until October 2000, potato wart in Canada occurred only in Newfoundland.