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Plant Industry Services - Plant Pathology Program

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

   Thousand Cankers Disease

What is Thousand Cankers Disease (TCD)?Photo of Thousand Cankers Disease.
Thousand Cankers Disease (TCD) is a disease complex of walnut, Juglans spp. which is caused by the fungus Geosmithia morbida and is vectored by the walnut twig beetle, Pityophthorus juglandis. The fungus causes the development of cankers beneath the bark of the tree.  As beetles attack the tree the number of cankers increases until they coalesce to girdle twigs and branches, restricting the movement of nutrients and eventually killing the tree. Thinning or dead branches will initially occur at the top of the tree, which will die from the top down. Trees may be infested for many years before showing symptoms.

TCD Detected in Virginia
On June 24, 2011, TCD was found in two black walnut trees in Chesterfield County, Virginia.  This was just the second time TCD had been found east of the Mississippi River; the first detection occurred in Tennessee in August 2010.  Neither the walnut twig beetle nor the fungus is native to the eastern U.S. and the presence of TCD poses a threat to Virginia’s black walnut trees.  Delimiting surveys conducted in the summer of 2011 confirmed additional walnut trees infected with TCD in Goochland, Hanover, Henrico and Powhatan counties and the cities of Colonial Heights and Richmond.  TCD was discovered in Fairfax, King William, New Kent and Prince William counties in 2012.

TCD Quarantine
On July 21, 2011, VDACS established a temporary quarantine in an effort to prevent the artificial spread of this disease to uninfested areas of the Commonwealth.  Effective January 2, 2012, the Thousand Cankers Disease Quarantine was made permanent.   As a result of additional TCD detections in Fairfax, King William, New Kent and Prince William counties, the TCD quarantine was expanded in 2012.  Localities now included in the quarantine include Chesterfield, Fairfax, Goochland, Hanover, Henrico, King and Queen, King William, New Kent, Powhatan and Prince William counties and the cities of Colonial Heights, Fairfax, Falls Church, Manassas, Manassas Park and Richmond.  The quarantine prohibits the movement of all walnut plants and walnut plant parts, including logs, stumps, firewood, roots, branches, mulch and chips out of the quarantined area.

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