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Home / Terrestrial Invasives / Terrestrial Pathogens and Diseases / Thousand Cankers Black Walnut Disease

Thousand Cankers Black Walnut Disease

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Thousand cankers disease -
Thousand Cankers Disease - Walnut twig galleries and cankers in branch of hybrid walnut; associated with walnut trig beetle Ned Tisserat, Colorado State University
Scientific Name: 
Geosmithia morbida (Kolařík et al. 2011)
Common Name: 
Thousand cankers black walnut disease (TCD)
Native To: 
Disease was first detected in the Western U.S.; the disease vector, the walnut twig beetle, is native to the southwestern U.S. and Mexico (Utley et al. 2013)
Date of U.S. Introduction: 
First observed in the 1990s, but not recognized until 2008 (Utley et al. 2013)
Means of Introduction: 
Unknown, but possibly through the transportation of logs and firewood (Randolph et al. 2013)
Fungal disease of walnut trees (Juglans spp.), particularly the black walnut (Juglans nigra), that is usually lethal within a few years; disease is transmitted by the walnut twig beetle, Pityophthorus juglandis (Tisserat et al. 2009)
Current U.S. Distribution: 
Widespread throughout the Western U.S.; first detected in the Eastern U.S. in Aug 2010


USDA. FS. Southern Research Station. CompassLive.

In recent decades, thousand cankers disease has become a concern for walnut growers and hardwood forest managers in the United States. A variety of measures have been investigated or developed to counter the disease. A study led by USDA Forest Service research entomologist Albert Mayfield and former University of Tennessee graduate student Jackson Audley looked at one measure: quarantine treatments. In an effort to stop the spread of the walnut twig beetle, certain states have prohibited the movement of regulated articles, including kiln-dried walnut lumber that still has its bark. The scientists investigated the risk of that type of lumber becoming colonized during movement to evaluate whether regulation of that product is necessary. Their paper was published in the Journal of Economic Entomology.

Distribution / Maps / Survey Status

University of Georgia. Center for Invasive Species and Ecosystem Health.
Provides state, county, point and GIS data. Maps can be downloaded and shared.


University of Georgia. Center for Invasive Species and Ecosystem Health.


Google. YouTube; University of Massachusetts - Amherst. 

Google. YouTube; University of Tennessee Extension (Knoxville County).

Selected Resources

The section below contains highly relevant resources for this species, organized by source. Or, to display all related content view all resources for Thousand Cankers Black Walnut Disease.

European and Mediterranean Plant Protection Organization.

National Plant Diagnostic Network.

You can become a more effective First Detector by familiarizing yourself with invasive target pests and pathogens known to exist in the U.S. If you think you have encountered one of the species or disease complexes listed, report its presence.

Nature Conservancy. Don't Move Firewood.

Ontario's Invading Species Awareness Program (Canada).

North Central Integrated Pest Management Center.

See also: Pest Alerts for more resources

North American Plant Protection Organization.

Thousand Cankers Disease.

Federal Government

USDA. FS. Northeastern Area State and Private Forestry.

USDA. FS. Northern Research Station.

USDA. Animal and Plant Health Inspection Service.
State and Local Government

Missouri Department of Conservation.

See also: For more information about Invasive Tree Pests (insects and diseases) that are not native to Missouri

Minnesota Department of Agriculture.

Tennessee Department of Agriculture.

Thousand Cankers Disease (TCD) poses a serious problem to the health of the black walnut tree. Tennessee Department of Agriculture officials urge area residents and visitors to help prevent the spread of TCD:

  • Don't transport firewood, even within Tennessee.
  • Don't buy or move firewood 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 to alert state plant and forestry officials, or call TDA's Consumer and Industry Services Division at 1-800-628-2631.

Kansas Department of Agriculture.

Thousand Cankers poses a serious threat to the health of black walnut trees. The Kansas Department of Agriculture, Kansas Forest Service and K-State Research and Extension need your help to help stop the introduction, and to limit the spread, of this disease in Kansas. We are deeply concerned that if it reaches the native range of black walnuts in central and eastern Kansas, we may lose this tree in our urban and native forests.

Indiana Department of Natural Resources. Entomology and Plant Pathology.

Maryland Department of Agriculture.

Thousand cankers disease (TCD) is a disease complex native to the western United States and primarily affects black walnut, Juglans nigra. This disease is the result of the combined activity of a fungus, Geosmithia morbida, and the walnut twig beetle WTB), Pityophthorus juglandis. On January 12, 2015, the the Maryland Secretary of Agriculture issued a quarantine order to minimize the risk of moving infested material out of the limited action area in Cecil County, and to provide confidence in Maryland walnut products moving into neighboring states from non quarantined areas. The 2015 quarantine order has been updated to include all of Baltimore City and part of Baltimore County (PDF | 1.2 MB). The new quarantine (PDF | 1.0 MB) was signed on May 1, 2019 by the Maryland Secretary of Agriculture.

University of Florida. Institute of Food and Agricultural Sciences.

Utah State University. Cooperative Extension.

See also: Landscape Ornamental Insects for more fact sheets
Kansas State University. Kansas Forest Service.
Ohio State University. Extension.
University of California. Statewide Integrated Pest Management Program.