Potato Wart Disease

Potato Wart Disease, also called potato canker, is a fungal disease of potato sprouts, eyes and stolons. It does not affect roots. The disease is primarily a disease of kitchen gardens where potatoes are cropped continuously; it is spread through the distribution of contaminated soil and potatoes, in droppings from animals fed infected potatoes, digging implements, footwear, etc. It is distributed worldwide, mainly in cool, moist environments.

In North America, the disease was first detected in Newfoundland in 1909 by Dominion Botanist H. Güssow. In 1912, Ottawa forbade the movement of Newfoundland soil and produce into Canada. This quarantine is still in effect, and ground transport leaving the island of Newfoundland is checked for the presence of soil or prohibited materials. In 2000 the disease was reported from several fields in Prince Edward Island and was the subject of extensive inspection and control measures by the Canadian Food Inspection Agency.

The disease-causing agent is a single-celled organism called Synchytrium endobioticum, a fungus (Chytridiomycetes) with a complicated life history. The most obvious symptoms of disease are soft, cauliflowerlike proliferations of tissue surrounding the infected cells. These warts or cankers are white at first but may become green if they enlarge and are exposed to light above the soil line. Eventually, wart tissue darkens and rots to release thick walled, persistent spores that can live for up to 40 years in the soil. As chemical control of wart is extremely difficult and may harm beneficial soil organisms, resistant varieties of potato are bred to control the disease. Alternatively, infested land is taken out of production.