Janine Hasey, University of California Cooperative Extension farm advisor, Sutter-Yuba counties, cuts into an English walnut tree to check for thousand cankers disease.
Janine Hasey examines bark for insect and disease damage.
A weakened English walnut tree killed by TCD.
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.
Located near the knife blade point is a one-tenth-inch-wide hole in the trunk drilled by the walnut twig beetle.
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.
Western Farm Press
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