Have you noticed all the dead ash trees around, now that the emerald ash borer has gotten well established in the state. Wonderful, isn’t it? Just the latest in a string of diseases, many consisting of fungus carried by boring beetles, that has hit eastern forests.

Well, here’s another one to worry about: oak wilt.

Yes, oak trees, which seemed like a boring but dependable fallback if climate change drives away all the maples, have a problem. The New Hampshire Division of Forests put out this warning today:

Oak Wilt disease has been in the Great Lakes region for decades but recent outbreaks in Albany and Long Island, New York have New Hampshire officials on alert. Red oaks – which have pointy-tipped leaves – are most susceptible to the disease and can die within a few weeks to six months of being infected. White oaks – which can be identified by round-tipped leaves – are less vulnerable.

Oak Wilt is a fungus that affects the vascular system of most oak species, stopping the movement of fluids throughout the infected tree, which then quickly dies of dehydration. 

The disease is spread over long distances through the transportation of infected logs and firewood. Over short distances, it is spread through root grafting as well as by beetles that ingest sap from infected trees and then travel to other trees.

Once an oak tree is infected with Oak Wilt disease, it cannot be saved. It is possible, however, to control and eradicate the disease’s spread to other trees, making it critical to find outbreaks early.

Trees with Oak Wilt disease are easily identified, as they drop their leaves during the summer, starting at the top of the tree.

Anyone noticing an oak tree that shed its foliage in July or August is asked to please contact the N.H. Division of Forests and Lands’ Forest Health Program at 603-464-3016 or to go to NHBugs.org and submit a report that can also include a picture.

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