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Thousand Cankers Black Walnut Disease

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

Thousand cankers disease -
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Thousand Cankers Disease


Walnut twig galleries and cankers in branch of hybrid walnut; associated with walnut trig beetle Ned Tisserat, Colorado State University

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  • Countering Thousand Cankers Disease

    • Sep 5, 2019
    • 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


Selected Resources

The section below contains highly relevant resources for this species, organized by source.

Federal Government
State and Local Government