Current distribution of 1000 cankers disease of black walnut and its vector, the walnut twig beetle (Pityophthorus juglandis)

The walnut twig beetle (Pityophthorus juglandis), in association with the fungus Geosmithia morbida, produces a devastating disease of black walnut (Juglans nigra) and some other Juglans species known as 1000 Cankers Disease. Extensive losses of Juglans due to this have been reported from most western states with extensive losses in some areas. The current distribution of this disease and its beetle vector will be summarized. Particular attention will be given to defining the eastern edge of this disease, which presently occurs in eastern Colorado.