This file photo shows tracks from emerald ash borers left in a black ash tree.

ST. PAUL — The Minnesota Department of Agriculture has placed Goodhue County under an emergency quarantine after emerald ash borer was found in the city of Red Wing.

During a hike over the weekend at Barn Bluff, an MDA employee noticed an ash tree with significant woodpecker damage, a tell-tale sign of possible emerald ash borer infestation. She took photos of the tree and noted the location. After further investigation, the MDA found EAB larvae in the tree.

The USDA on Friday officially confirmed the insect to be emerald ash borer.

Because this is the first time EAB has been identified in Goodhue County, the MDA is enacting an emergency quarantine to limit the movement of firewood and ash material out of the county to help reduce the risk of further spreading the tree-killing insect. Fourteen other Minnesota counties are under quarantine to prevent the spread of the emerald ash borer.

"Our staff led by example and followed the advice we've been giving for years, which is, it's important that people go out into their yards, parks and natural areas and look for signs of EAB," said Geir Friisoe, director of MDA's plant protection division.

"The trees are still bare, and the weather is warmer, so this is the perfect time to look for woodpecker damage and other signs of an emerald ash borer infestation."

There are several things residents should look for when checking for emerald ash borer.

• Be sure you've identified an ash tree. This is an important first step because EAB only feeds on ash trees. Ash have opposite branching — meaning branches come off the trunk directly across from each other. On older trees, the bark is in a tight, diamond-shaped pattern. Younger trees have a relatively smooth bark.

• Look for woodpecker damage. Woodpeckers like EAB larvae, and woodpecker holes may indicate the presence of EAB.

• Check for bark cracks. EAB larvae tunneling under the bark can cause the bark to split open, revealing the larval (S-shaped) tunnels underneath.

• Contact a professional. If you feel your ash tree may be infested with EAB, contact a tree care professional, your city forester or the MDA at arrest.the.pest@state.mn.us or 888-545-6684 (voicemail).

Minnesotans also can help stop the spread of EAB by burning firewood where you buy it and not transporting it. Look for wood that is MDA certified as heat-treated to ensure it is pest-free.

Emerald ash borer larvae kill ash trees by tunneling under the bark and feeding on the part of the tree that moves nutrients up and down the trunk. The invasive insect first was discovered in Minnesota in 2009 and now is found in 30 states.

Minnesota is highly susceptible to the destruction caused by EAB. The state has about 1 billion ash trees, the most of any state in the nation.

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