SOUTH BRISTOL — The New York State Department of Environmental Conservation (DEC) announced last week that oak wilt, a disease that affects oak trees, has been detected in South Bristol, Ontario County.

This is the second location in Ontario County where oak wilt has been confirmed. The disease was confirmed in the town of Canandaigua in 2016. Ontario County is one of four counties in the state that have confirmed oak wilt infections. Other counties with confirmed cases of oak wilt are Kings, Suffolk, and Schenectady counties.

A concerned landowner contacted DEC after several oak trees on their property in South Bristol began showing signs of oak wilt, including dropping discolored leaves in July and then dying rapidly. Samples from one of the trees were sent to the Cornell Plant Disease Diagnostic Clinic where they tested positive for the fungus that causes the disease. The current treatment method to contain and kill the oak wilt fungus is to remove the infected trees, as well as any nearby oaks that could become infected.

DEC will issue an order establishing a quarantine district prohibiting the movement of oak material out of the immediate area to prevent the fungus from spreading. In addition, DEC will conduct aerial and ground surveys over the next few weeks to identify additional trees that may be infected. Impacted property owners will be contacted with information about oak wilt and to provide them with information about how to help protect remaining oak trees.

During the winter months, DEC will remove infected trees. Surveys will resume in the spring, when dead trees and signs of the fungus may be more apparent.

Oak wilt, caused by the fungus Bretziella fagacearum, is a serious tree disease in the eastern United States, killing thousands of oaks each year in forests, woodlots and home landscapes. As the tree attempts to defend itself, it produces gummy plugs to restrict the movement of the fungus. These plugs, together with the growing fungus, prevent the water transport in the tree. As water movement within the tree is slowed, the leaves wilt and drop off, and eventually the tree dies.

DEC asks the public to report any occurrences where an oak tree died over a short period of time, especially if it occurred between July and August, to the Forest Health Information Line toll-free at 1-866-640-0652.

For more information about oak wilt, please visit DEC's website.