Spare the Shears to Stop Wilt

The State Department of Environmental Conservation has warned against spring and summer pruning of oak trees, which have become infected across the state and Suffolk County with a disease called oak wilt.

Beetles that can spread the disease are active in spring and summer and are attracted to freshly cut or injured healthy trees, according to the D.E.C., and so could carry the fungus from sick to unaffected trees if pruning takes place now. If pruning is needed, it should be done between October and February, according to the state.

A fungus that blocks water and nutrients and causes leaves to wilt and drop off, the disease has been killing thousands of oak trees in the eastern United States annually and is expected to make its appearance in East Hampton Town this summer. The state agency will undertake sampling and aerial surveys to check for oak wilt in July, when it is most apparent. Infected trees will have to be cut down.

Oak wilt is one of the most destructive tree diseases, and can kill trees in as little as four to six weeks. Symptoms include discoloration around leaf edges and sudden loss of a substantial portion of leaves during the summer months.

Earlier this year, the D.E.C. issued an emergency order creating a protective quarantine zone encompassing the entire county. It prohibits the transport outside the county of oak wood, or firewood logs of any species, as it is difficult to determine whether cut logs are oak or not. Protective zones have also been established throughout the state.

All oak trees can come down with oak wilt disease, but red oaks are particularly susceptible; they die faster from the fungus than white oaks, and spread the disease more readily.

The fungus spreads through tree roots below ground, and is spread above ground by the beetles, which feed on tree sap and bark. Beetles can spread oak wilt spores throughout an area of several miles.

The D.E.C. has encouraged people to report possible instances of oak wilt to its Forest Health office, by phone at 866-640-0652 or by email to [email protected].  Photos of the symptoms should be included.