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Thousand Cankers Disease (TCD)


Thousand Cankers Disease (TCD) poses a serious problem to the health of the black walnut tree. Walnut trees are important because of their nut crop and the desired wood for various products. TCD is a progressive disease that kills a tree within two to three years after initial infection. The disease-causing fungus, Geosmithia, is transmitted by a small twig beetle. Branches and trunk tissue are killed by repeated infections by the fungus, as the beetles carry the fungus into new bark cambium tissue.

Cures for TCD have not yet been identified and their development will require better understanding of the biology of the walnut twig beetle and the canker-producing Geosmithia sp. Rapid detection and removal of infected trees currently remains the primary means of managing thousand cankers disease.

TDA officials urge area residents and visitors to help prevent the spread of TCD:

  • Don't transport firewood, even within Tennessee. Don't bring firewood along for camping trips; get the wood from a local source. Don't bring wood home with you.
  • Don't buy or move firewood from outside the state. If someone comes to your door selling firewood, ask them about the source, and don't buy wood from outside the state.
  • Watch for signs of infestation in your walnut trees. If you suspect your walnut tree could be infected with TCD, refer to the TCD Symptoms Checklist and online TCD Report Form to alert state plant and forestry officials, or call TDA's Consumer and Industry Services Division at 1-800-628-2631.

Counties Under Quarantine

Anderson, Blount, Jefferson, Knox, Loudon, Morgan, Rhea, Roane, Sevier and Union. Citizens in these counties cannot move walnut tree products and hardwood firewood outside the quarantined counties.