Oak wilt has invaded New York State


There is more to worry about our beautiful trees. It’s bad enough to hear about the emerald ash borer impacting our ash trees and the hemlock woolly adelgid attacking our hemlocks. Another problem to worry about concerns our oak trees.

Recently, the New York State Department of Environmental Conservation (DEC) confirmed that oak wilt, a tree fungus that causes diseases in oak trees, has spread to a fifth county in New York State. The disease has been confirmed in Yates County town of Middlesex after a homeowner contacted the DEC.

To date, the disease has been found in Ontario, Suffolk, Schenectady, Kings and now Yates counties. If left untreated, this disease can spread and kill our precious oak trees. All oaks appear to be susceptible; however, red oaks seem to die faster than white oaks.

Oak wilt was first detected in Wisconsin in 1944 from which it spread throughout the Midwest and Texas killing thousands of trees; where the disease originated from is still unknown.

The disease made its first appearance in New York in the Schenectady County town of Glenville in 2008. Despite a quick response to remove and destroy infected trees, additional infection sites resurfaced. Oak wilt can spread below ground through the tree roots and above ground by certain types of beetles.

It’s a serious problem because the fungus blocks the flow of water and nutrients from the roots to the crown, causing wilt, and eventually killing the tree. Unfortunately, there is no known treatment at the present time other than to remove infected trees.

If you have oak trees, be vigilant. Learn to recognize the symptoms including leaf discoloration, rapid leaf loss, and fungal spore mats. Brown coloration can develop on leaves starting at the outer edge and progressing inward toward the mid-veins of the leaves. Leaves can suddenly wilt. Leaf loss can occur at odd times such as spring or summer and leaves may fall prematurely. Branch dieback can start at the top of the tree canopy and progress downward. There may be fungal mats under the bark which causes the bark to raise and split.

Avoid pruning or wounding oak trees in the spring and summer, when spore mats are present, and beetles are the most active. If an oak wound occurs during spring or summer, it should be sealed with wound covering to deter beetles from going to those areas.

A professional diagnosis is the best way to determine if your tree is infected. Samples from the tree are normally required and are sent to the Cornell Plant Disease Diagnostic Clinic, where they can be tested and confirmed. If you are concerned about your oak tree, you should contact the Cornell Plant Disease Clinic or the NYS Department of Environmental Conservation.

Visit Cornell’s website for more information at plantclinic.cornell.edu. The DEC can be reached at 866-640-0652 or via email at foresthealth@dec.ny.gov. Visit the New York State Department of Environmental Conservation’s Forest Health website at www.dec.ny.gov for more information about this disease.

For more information go online to cceoneida.com or call the horticulture hotline on Wednesday and Friday between the hours of 9AM to noon, 315 736 3394.


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