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Thousand Cankers Disease

Photo of Thousand Cankers Disease

Photo by: Curtis Utley, CSUE,

Thousand Cankers Disease (TCD) of Eastern Black Walnut

First Detection in the East

Background and Concerns:
On August 5, 2010, the Tennessee Department of Agriculture announced that TCD was confirmed in Knoxville, TN. This is the first confirmation of the disease within the native range of eastern black walnut. It was found on urban street trees. It is possible that other infected trees exist within the native range of eastern black walnut. TCD is caused by the walnut twig beetle (Pityophthorus juglandis) and a fungus it vectors, Geosmithia sp. Nov. (tentative species name morbida). Neither the beetle nor the fungus are thought to be native to the eastern US. The beetle is native to the southwest and Mexico. The origin of the fungus is unknown. The association with the beetle was not previously known. TCD was first observed in New Mexico in the 1990’s. It has since spread to most western States killing eastern black walnuts. The tree has been planted extensively in the west since the 1850’s. TCD also affects other black walnuts native to the west. Outbreaks of the twig beetle are thought to have coincided with the recent long term drought. In the western US it takes about 8-10 years of continuous feeding of the beetle to deliver enough fungus to kill a black walnut tree. It is not known how the beetle and fungus will act and what the impact of TCD might be in native eastern black walnut ecosystems. Movement of infected black walnut could further spread TCD.

Additional TCD Information:

Thousand Cankers Disease Pest Alert

Southern Region (R8) TCD Information

TN Department of Agriculture: Thousand Cankers Disease

Method for Isolating and Maintaining Cultures of Geosmithia from Juglans nigra

Check-Off List for Selecting Symptomatic Black Walnut to Sample for TCD

Suspect tree reporting form (outside the State of Tennessee)

Sample form (for cooperators wishing to develop a survey)

Thousand Cankers Disease Photos

Thousand Cankers Disease Map