Thousand Cankers Disease is Widespread in Black Walnut in the Western United States

Thousand cankers disease of black walnut is caused by aggressive feeding by the walnut twig beetle and subsequent canker development around beetle galleries caused the fungus Geosmithia morbida. The authors We confirmed the presence of G. morbida from symptomatic black walnut or hybrids in California, Colorado, Idaho, New Mexico, Oregon, Utah, and Washington. Thousand cankers disease continues to cause extensive mortality to black walnut over a wide geographic region and is intensifying in the western United States. Accepted for publication 2 June 2011. Published 30 June 2011.