ST. PAUL — Minnesota officials have confirmed trees in Olmsted County are infested with the destructive emerald ash borer.

The state Department of Agriculture said Wednesday the county will join Hennepin, Houston, Ramsey and Winona counties in a state and federal quarantine to prevent the infestation from spreading. That means ash logs, lumber, chips and tree waste can’t be taken out of the county without a department certificate.

The larvae of the emerald ash borer beetle kill ash trees by tunneling into the wood and feeding on the tree’s nutrients. Minnesota has approximately one billion ash trees, more than any other state.

The infested trees are about 45 miles away from the nearest infestation in Winona County, near the interchange of Interstate 90 and U.S. Highway 63.