Thousand Cankers Disease
While this disease poses a serious threat to black walnut in its native range, it is not yet known how the twig beetle or the canker fungus will behave under eastern conditions.
The beetle (Pityophthorus juglandis) is native to the southwestern US and Mexico. The canker fungus, Geosmithia sp. nov. (proposed species name is morbida), is new to science and to date is only known in association with the beetle; however, it is a relatively non-aggressive fungus that only has a serious affect in a tree after thousands of individual beetle attacks (inoculation points), hence the common name for this malady.
It is now imperative that eastern black walnuts recently dead or with fading foliage, dying twigs and branches, be carefully examined and sampled for the presence of the beetle and fungus. It is particularly important that qualified experts be consulted when this is done. Samples need to be carefully handled and sent only to laboratories which are authorized to handle such specimens and have the expertise to identify these agents. If in doubt about who to call or consult, check first with your State Forestry Agency or State University Extension Service.