A Purdue forestry and natural resource specialists warns that Indiana property owners ought to be on the lookout for a disease that could spread to walnut trees here from neighboring Ohio.
Elizabeth Jackson, who also serves as executive director of the Purdue-based National Walnut Council and the Indiana Forestry and Woodland Owners Association, said “Healthy trees are less affected, so keeping your trees healthy and vigorous will help reduce the risk” of getting thousand cankers disease.
The disease was discovered in Ohio recently. “Residents need to know that thousand cankers disease has not been found in natural areas yet, but almost every incident has been in an urban, industrial or an area outside the suburbs,” Jackson said.
The disease has no known treatment and is the result of walnut twig beetles carrying a fungus, damaging tree tissues.
Jackson said firewood and other types of untreated wood should not be transported. Many insect infestations, including some involving TCD outbreaks, result from infested wood being moved into an uninfested area.
“There are very stringent requirements on firewood now,” Jackson said.
Symptoms of TCD commonly include thinning crowns, yellowing or wilted leaves in the crown and limbs that died recently. But Jackson said leaves turning yellowish in August and September and falling off the tree are not necessarily symptoms of TCD. They can be symptoms of anthracnose, an unrelated disease, or drought stress. The leaves of a tree infected by TCD will wilt but stay attached to the tree.
Tree owners observing a black walnut tree with yellow leaves on the outer branch in the tree crown through September can file a report through the Forest Pest Outreach Survey on the Indiana Department of Natural Resources website at www.in.gov/dnr/entomolo/7416.htm. They also can print the form and send it by fax or email, or call 866-663-9684.