Oak tree disease detected across the North Fork

oak wilt

A deadly and fast-spreading disease has been detected in oak trees in Southold and Riverhead towns, according to two state organizations.

The state departments of Environmental Conservation and Agriculture and Markets announced last Thursday that the disease, known as oak wilt, was identified by the Cornell Plant Disease Diagnostic Clinic after sampling symptomatic trees.

Oak wilt is caused by a fungus that blocks the flow of water and nutrients from a tree’s roots to its branches and leaves. As a result, leaves wilt and drop off, causing the tree to die quickly.

“It works like a weed killer,” said Ned Harroun, a certified arborist and owner of Southold-based Island Tree Co.. “When you spray weed killer on a lawn or weed, what is does is interfere with the plant’s ability to conduct water, to take moisture out of the ground.”

He likens the disease to a cancer.

Symptoms can be spotted especially in the summer, when oak leaves wilt and look smaller or unseasonably brown. The wilt would show on the outer fringes of the foliage, Mr. Harroun said.

“If you can imagine an umbrella and the outer part where the rain drips off, that would be all kind of burnt and rolled and maybe even have little speckles in it,” he said, describing an infected tree’s canopy.

Oak wilt appeared in Central Islip last spring and has since been found in Brooklyn as well. At the time, the DEC issued an emergency order to dispose of any infected tree material and designated a protective zone around the affected neighborhoods.

The DEC is preparing to issue a broader emergency order establishing a protective zone encompassing Suffolk County in its entirety, which will prohibit the removal of any living, dead, cut or fallen oak trees and bits such as branches, stumps or roots unless they have been chipped to less than an inch. The agency will also conduct aerial surveys beginning in July, when signs of oak wilt are more noticeable.

“It is important that these emergency orders are taken seriously,” DEC commissioner Basil Seggos said in a statement issued Dec. 29. “Moving contaminated wood without taking precautions will spread this serious tree-killing disease to additional areas.”

Education is key in detecting and stopping the spread of oak wilt, said Mr. Harroun, who hasn’t yet received calls for tree removals related to the disease.

There’s no known treatment to kill the oak wilt fungus other than to remove infected trees and surrounding host oaks, according to the DEC. The agency said in a statement it will remove and destroy any trees that test positive for the fungus and that testing will pick up come spring, when the fungus is active.

The disease was detected at Wildwood State Park in Wading River and the Little Hog Neck neighborhood in Cutchogue, the DEC said.

The DEC announced it will contact property owners in neighborhoods where oak wilt is confirmed to provide information on the disease and, once its extent is determined, will look to hold public meetings to address questions and concerns.

Residents can report oak wilt by calling the DEC Forest Health office at 866-640-0652 or by emailing photos to verify symptoms to [email protected].

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Photo credit: NYSDEC