The New York State Department of Environmental Conservation (DEC) has expanded the oak wilt quarantine districts in Yates and Ontario counties in the Finger Lakes after finding new trees infected with oak wilt.
The two quarantine districts have been combined into one, which now includes the entire towns of Middlesex, Italy, and South Bristol, and parts of the towns of Bristol and Naples. Movement of oak wood out of the quarantine district is restricted to help limit the spread of oak wilt while DEC treats the infected sites and monitors the area for additional infections.
“Oak wilt can have a devastating impact on private and state lands,” said DEC Commissioner Amanda Lefton. “Expanding the quarantine district in the Finger Lakes is a necessary step to stop the spread of this destructive disease and protect the long-term health of our forests. Oak trees are an important part of our environment and local economies, and DEC is committed to working with communities, landowners, and industry partners to safeguard these vital resources.”
DEC detected discolored oak trees during aerial surveys in July 2025. Further evaluation of branch and leaf samples by Cornell University Plant Disease Diagnostic Clinic confirmed the presence of oak wilt on seven sites in the towns of Middlesex, Italy, South Bristol, and Naples — four on private lands and three in DEC’s High Tor Wildlife Management Area.
DEC cut down the infected oaks and, as a precaution, some neighboring oaks that were not symptomatic as well. To prevent further spread, stumps were treated with herbicide to kill the roots, and logs and branches were chipped or burned to prevent the growth of fungal spore mats.
DEC said it will monitor the stumps for resprouting and neighboring oak trees for oak wilt symptoms. Aerial surveys around positive detections are expected to continue for at least the next five years.
Oak logs and branch debris are prohibited from leaving the quarantine district unless they are chipped to less than one inch in two dimensions. Non-oak wood is also restricted unless it is in lengths of 29 inches or greater for identification purposes.
Limited Transportation Permits are available to move oak wood and firewood out of the quarantine district during the fall and winter months. A map and description of the quarantine district can be found on DEC’s website.
Oak wilt was first discovered in New York State in 2008 in the Town of Glenville, Schenectady County. Over the course of a decade, DEC managed a total of five infection sites in the Glenville area, which included the removal and disposal of 203 oak trees across 23 properties.
No new infections have been found since 2018, prompting the lifting of the quarantine district. DEC says it continues to monitor oaks in the area for signs of new oak wilt infections.
Other inactive infection centers include the towns of Islip, Southold, and Riverhead in Suffolk County; Green-Wood Cemetery in Brooklyn; and Canandaigua in Ontario County.
In 2023, oak wilt was found near the Western New York border in Ontario, Canada. To date, no evidence of spread from Canada into New York has been observed. Residents of this area, as well as other areas with oak wilt across the state, are encouraged to watch for oak wilt symptoms and report if seen.
Oak wilt is a serious tree disease that was first discovered in Wisconsin in 1944. Since that time, it has spread, killing thousands of oak trees each year. Oak wilt is caused by a fungus, Bretziella fagacearum, which blocks the water conducting vessels (xylem) of host trees, slowing the transport of water and causing the leaves to wilt and drop off.
Infected red oak trees typically die within a few weeks of being infected. The disease is spread through interconnected root systems and by beetles that pick up the fungal spores from fungal mats on infected trees and transport them to other oaks. In addition, the spread of oak wilt disease is associated with the movement of firewood and other wood products.
For more information, visit DEC’s webpage, email DEC at foresthealth@dec.ny.gov or contact your local DEC Lands and Forests Office.
Read more about oak trees in New York State.
Illustration: Leaves from a red oak tree infected with oak wilt (courtesy DEC).
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