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    Thousand cankers disease (TCD) is a growing threat to black walnut, an economically and ecologically important tree in the eastern US. Trees in the earliest stages of TCD do not display symptoms. In later stages, leaves of the canopy become yellow, wilt, and ultimately die, yet remain attached to their branches. Eventually, all branches in the canopy may die, leading to tree death. TCD is caused by the fungus, Geosmithia morbida that is carried by walnut twig beetles (Pityophthorus juglandis) attracted to walnut trees. After landing on a tree, the beetles bore into the inner bark to create egg galleries. The fungus spreads from galleries and creates small bark cankers

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    Reed, Sharon; English, James; Juzwik, Jennifer; Ginzel, Matt. 2013. Bark and ambrosia beetles and their associated fungi colonizing stressed walnut in Missouri and Indiana. Walnut Council Bulletin. 40(2): 17-19.

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