Frequently Asked Questions

What is thousand cankers disease (TCD):  TCD is caused by a fungal pathogen (Geosmithia morbida) vectored by the walnut twig beetle (Pityophthorus juglandis).


How does thousand cankers disease kill a tree: Adult beetles carry the fungus on their bodies; the fungus enters the tree when beetles feed or bore into the bark and form galleries, where they spread the fungus; the fungus forms small cankers (areas of dead tissue) which disrupt nutrient and water flow. The fungus causes small cankers throughout the infested area of the tree. These coalescing cankers disrupt cambial and phloem function (i.e., nutrient and water flow) within the tree. Over several years and after thousands of cankers, trees die.


How long does it take for thousand cankers disease to kill a tree: Trees die within two to three years after they begin to show symptoms of dieback and excessive wilting. However, it is important to note that the tree may have been infested with the beetle for 10 or more years before symptoms develop.


How does thousand cankers disease spread: DON’T MOVE FIREWOOD! The fungus and the beetle can spread through transportation of infected/infested wood. Wood carvers should be diligent in ensuring that they obtain wood from non-infested/infected areas. Thousand cankers disease has not been shown to be spread by nuts or by nutmeat.


Where has thousand cankers disease (TCD) been found: In 2010, this deadly disease was found on black walnut in its native range in the eastern U.S. (Tennessee). In 2011, TCD was found in Pennsylvania, and Virginia. In 2012, TCD was found in North Carolina and the walnut twig beetle was found in Ohio. In 2014, the pathogen was found on a weevil collected from a stressed black walnut tree in Illinois. Surveys continue to assess distribution of walnut twig beetle and TCD across the United States.


What are the symptoms of thousand cankers disease (TCD):  Symptoms of TCD resemble drought stress, which causes this disease to often go undetected. One of the first symptoms is flagging – one or more branches with yellow foliage. Other symptoms include wilting, clinging foliage, limb and/or canopy dieback, and profusion of epicormic shoots (i.e., water sprouts) near the base of the trunk.  You also can examine the branches and tree trunk for entrance/exit holes, where the small beetles entered or left the tree. It is best to use a magnifying lens when examining the tree because the holes are small and may be difficult to see


What can you do:  DON’ T SPREAD IT! Don’t transport firewood! If camping, purchase firewood at your destination. Don’t bring wood with you or return home with unused wood. Buy firewood or wood for woodworking from a local source.  Avoid any conditions that may stress your tree (i.e., water during drought-like conditions).


What do I do if I believe that I have thousand cankers disease (TCD) on my black walnut:If you believe that you have symptoms similar to TCD on your black walnut trees, contact your county agent, state forester, or state department of agriculture for further information. Help reduce the spread, report suspect trees!

Thousand Cankers Disease Links

Thousands Cankers Disease


TN Dept. of Agriculture - TCD


Colorado State University - TCD


Pennsylvania Dept. of Agriculture - TCD

Find more helpful TCD links here