To curb the spread of oak wilt, a fast-moving and potentially fatal tree disease caused by fungus, Suffolk County has been named a “protective zone,” the state Department of Environmental Conservation announced Tuesday.

Suffolk residents are prohibited from removing from the zone “any living, dead, standing, cut, or fallen oak trees or any portion thereof ... unless ... chipped to less than one inch in two dimensions,” the DEC said.

That would include “branches, logs, stumps, or roots, green oak lumber, and firewood of any species.” All firewood is included because, when cut into small pieces, it’s hard to tell oak from other species.

The fungus spreads easily from tree to tree, whether the infected tree is dead or alive.

“Across the country, oak wilt has killed tens of thousands of trees, resulting in hundreds of millions of dollars in damages and economic loss,” DEC Commissioner Basil Seggos said. Oak is widespread and valuable hardwood in New York, which is working to stop losses of oak trees, he said.

There is no known treatment for the disease, which kills thousands of oaks a year in the eastern United States the DEC said. In December the agency announced the disease had been detected in the towns of Babylon, Islip, Riverhead and Southold.

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At that time emergency orders were in the works to designate Suffolk County and Brooklyn, where the disease also has been confirmed, as protective zones, the DEC said. Moving contaminated wood without taking precautions could help spread the disease, Seggos said at the time.

The DEC said it is now removing infected trees and will test for the disease during the growing season when the fungus is active. It will conduct “intensive sampling” starting in June, with aerial surveying starting in July.

The public can report any oak trees that suddenly lose their leaves in July or August to the DEC’s forest health experts.

Call 866-640-0652 or email foresthealth@dec.ny.gov, including photos showing oak wilt.

Learn more at www.dec.ny.gov/lands/46919.html.