Crops >Orchard Crops  Photos: thousand cankers disease in California walnuts Jul 06, 2011 1. 1-1-1-1.JPG Janine Hasey, University of California Cooperative Extension farm advisor, Sutter-Yuba counties, cuts into an English walnut tree to check for thousand cankers disease. 2. 2-2-2-2.JPG Janine Hasey examines bark for insect and disease damage. 3. 3-3-3-3.JPG A weakened English walnut tree killed by TCD. 4. 4-4-4-4.JPG Symptoms of walnut species with TCD include thinning foliage in the tree’s upper crown followed by dieback of large branches and eventual tree collapse. 5. 5-5-5-5.JPG Located near the knife blade point is a one-tenth-inch-wide hole in the trunk drilled by the walnut twig beetle. 6. 6-6-6-6.JPG Bleeding and staining is heavy from TCD on this Chico variety English walnut tree on black walnut rootstock in Tulare County. Photo by Elizabeth Fichtner.