Emerald ash borer in St. Clair 2 (copy)

The signature S-shape grooves of emerald ash borer larvae are visible after bark was peeled away from an infected tree in March 2021 at the city park in St. Clair in Blue Earth County.

The Minnesota Department of Agriculture has confirmed emerald ash borer in Nicollet and Redwood counties for the first time.

Thirty Minnesota counties, including Blue Earth County, now have EAB. The pest was first discovered in Minnesota in 2009 and kills ash trees.

An MDA employee was surveying for EAB near reported infestations in Brown County when he noticed ash trees with signs of EAB at Sailors and Soldiers Memorial Park Campground in Sanborn in Redwood County and across the Minnesota River from New Ulm in Lafayette Township in Nicollet County, according to a news release from the ag department.

Both sites are fewer than 10 miles from previously confirmed infestations. MDA staff members were able to find live larvae and collect samples for federal identification.

Because this is the first time EAB has been identified in Nicollet and Redwood counties, the state ag department is enacting emergency quarantines to limit the movement of firewood and ash material out of the counties. The MDA issues quarantines for all counties known to have the ash borer to reduce the risk of further spreading the tree-killing insect.

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. Often the trees show several signs of infestation. Woodpeckers like to feed on EAB larvae and woodpecker holes may indicate the presence of emerald ash borer. Also, the EAB tunneling can cause the bark to split open, revealing characteristic S-shaped galleries underneath.

Allen Sommerfeld, MDA public information officer, said a crew has been inspecting areas near spots in Brown County where signs of the borer had been previously found. A growth of trees near the Highway 15/Highway 14 intersection north of New Ulm caught the attention of one of the staff members.

"It was a different situation from how we usually receive reports," Sommerfeld said.

MDA mainly relies on reports from tree removal services and from county University of Minnesota Extension offices.

Ag Extension educator Emma Severns was disturbed but not surprised when she received notice Tuesday that EAB had been found for the first time in her county.

“Obviously, it's upsetting; but I knew it was just a matter of time before Nicollet County had it ourselves,” Severns said.

She also serves Sibley County, where evidence of the invasive insect was confirmed in 2020.

This summer Severns kept watch for tree-killing larvae and fielded calls from residents who suspected infestations on their properties. Her investigations showed no presence of the ash borers, although Severns suspects the pests' arrival to the western side of Nicollet County was much earlier than this month.

Sommerfeld said the MDA's next step regarding the Nicollet County infestation will be to determine who owns the land where the trees are located. Removal of the trees would be the responsibility of either the Minnesota Department of Transportation or a local property owner.

"Now that we know it's here, we can get to work on educating the public about how to identify EAB and how to report it," Severns said.

She recommends Nicollet County residents attend the MDA's virtual informational meeting and that they go to the Extension Service's website and search for EAB information.

Virtual informational meetings for residents and tree care professionals will be Dec. 15. Experts from the MDA will give a presentation followed by a question-and-answer session. The meetings are 10-11 a.m. or 6:30-7:30 p.m. Register at www.mda.state.mn.us/eab.

The public also will have an opportunity to provide input on the proposal to add Nicollet and Redwood counties to the state formal quarantine. The MDA is taking comments on it through Jan. 6 and recommends adopting the quarantine Jan. 10. The quarantine limits the movement of ash trees and limbs and hardwood firewood out of the counties.

The quarantine language can be found at www.mda.state.mn.us/eab. Comments can be made during the virtual meeting or by contacting: Kimberly Thielen Cremers, MDA, 625 N. Robert St., St. Paul, MN 55155 or email Kimberly.TCremers@state.mn.us.

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