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

Fig. 5. (A and B) Bark has been removed to reveal the elongate, diffuse trunk cankers that develop during the final stages of the disease. Geosmithia was consistently isolated from the discolored bark whereas both Geosmithia and Fusarium solani were isolated from the cambium at the canker margins. Approximately ¾ of the trunk circumference (clockwise from top to bottom arrow) has been killed.



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