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Plant Industry Services - Plant Pathology Program

Plant Pathology
Facilities and Contacts
How to Submit a Sample
Updates and Reports

Diseases of regulatory concern
   Box blight (Cylindrocladium pseudonaviculatum=Cy. buxicola)
   Chrysanthemum white rust
   Phytophthora ramorum
   Plum pox virus
   Potato cyst nematodes

   Thousand Cankers Disease

Potato cyst nematodesPhoto of Potato cyst nematodes.

There are two species of potato cyst nematodes (PCNs) – the pale cyst nematode (Globodera pallida) and the golden cyst nematode (Heterodera rostochiensis). Both species are thought to be native to regions of the Andes mountains, the center of origin of potatoes. PCNs were likely introduced to Europe around the 1850’s on stock collected for genetic improvement trials after the great potato blight of 1845. Both pathogens feed on potato roots which causes significant reduction in tuber yield and plant health. PCNs were not detected in the U.S. until 1941 when the golden nematode was discovered in Long Island, NY potato fields.  In 2006, the pale cyst nematode (Globodera pallida) was detected in soil from an eastern Idaho potato grading facility. The find caused Canada, Mexico, and Korea to temporarily ban the import of potatoes from Idaho while Japan stopped importing potatoes from the entire United States.  Most countries lifted bans on U.S. potatoes only after intensive surveys were conducted throughout Idaho showing infestations were localized. Since 2007, VDACS has tested 420 soil samples for PCNs, representing 420 field acres. PCNs have not been detected in Virginia.

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