Black Walnut Mortality in Colorado Caused by the Walnut Twig Beetle and Thousand Cankers Disease

Fig. 2. (A) Gallery formation caused by walnut twig beetle adult in Julgans nigra branch. Note the extensive discoloration surrounding galleries caused by Geosmithia.



Image from Plant Health Progress article:
Black Walnut Mortality in Colorado Caused by the Walnut Twig Beetle and Thousand Cankers Disease