Thousand Cankers Disease Threatens Black Walnut
Posted: October 10, 2011
Walnut twig beetle adults on thousand cankers of black walnut. Photo from University of Illinois Extension
Article by Scott Guiser, Penn State Extension, Bucks County
Visit Scott's blog!
A species is at stake. Businesses are at stake. Both may survive but damage has already been done and the future is uncertain.
Black Walnut, Juglans nigra, is an important tree species in the eastern United States. In July of this year, Thousand Cankers Disease (TCD) was detected in Pennsylvania for the first time. We now join two other states east of the Mississippi with confirmed cases of a disease which is deadly to black walnut.
A quarantine has been established by the Pennsylvania Department of Agriculture in an effort to slow the spread of the disease. The quarantine prohibits the movement of walnut out of Bucks County, the only county in Pennsylvania where detection has occurred. All firewood and wood chips are also subject to the quarantine since segregation of walnut from these potential infection sources cannot be assured.
In summary, a new disease of Black Walnut threatens an important tree species. Sadly, we've seen situations like this before; Chestnut Blight, Dutch Elm Disease (DED), Hemlock Woolly Adelgid. Perhaps Dutch Elm Disease is most similar because in both cases a beetle vectors a fungal pathogen.
Decades after Dutch Elm Disease was introduced, we still have
some elms, but the once loved American Elm has been seriously impacted.
Many differences exist between DED and TCD but its probably a good place
to start as we contemplate the effect of TCD in Pennsylvania. How the
story of Thousand Cankers Disease of Black Walnut will play out remains
to be seen.
Here are some questions and answers about Thousand Cankers Disease.