'X' marks demise of ash trees

Pink isn't a good color for city ash trees these days. That's because Cloquet trees marked with bright pink dots (and some with large X marks) are short-timers, doomed to be cut down in response to the invasion of the emerald ash borer. Five trees in a row bear the mark on Eighth Street, and another five or six on 17th Street sport pink accents.

The list of city ash trees affected by the emerald ash borer (EAB) has grown from 20 to 32 since mid-December, when Cloquet public works director Caleb Peterson announced the city will receive a $428,000 grant for community forestry work from the Minnesota Department of Natural Resources.

"Winter is the best time to remove the trees," said Cloquet engineering technician and project manager Joe Hafner. "We're trying to do it before the ash beetle emerges in the spring. And we are trying to prevent infection of other trees."

EAB is an insect that attacks and kills ash trees. The adults are small, iridescent green beetles that live outside of trees during the summer months. The larvae are grub or wormlike and live underneath the bark of ash trees. Trees are killed by the tunneling of the larvae under the tree's bark. EAB spreads through short-distance natural flight and long-distance transport of infested firewood. The invasive insect was first discovered in Cloquet (and Carlton County) in April 2022.

There are now 47 counties in the state with known EAB infestations.

Long-term, residents should expect some changes in scenery, Hafner said.

"We believe the city has about 1,000 ash trees in public areas, and hundreds of them will be cut down," he said. "Although trees will be planted to replace them, it's going to take some time for them to mature."

Hafner said almost all of the currently marked ash trees are located in city boulevards, with a few in city park areas. The trees that are removed will be replaced by another species of tree. Hafner said the replacement species is yet to be determined.

"The DNR wants us to diversify our urban forest," he said. "We already have a lot of maple in town, so it probably won't be that."

As part of the grant process, the city is working with a certified arborist to inventory all city-owned trees and put together a management plan that will identify best practices for years to come. Hafner said people should not mark any public trees themselves and create confusion for city staff and contractors.

The city or its contractors will not be removing trees on private property, but Hafner suggested residents learn to identify if they have ash trees on their property and prepare for any needed mitigation.

Emerald ash borer signs:

• Woodpecker activity is a top sign of tree infestation, as well as S-shaped feeding marks left under the bark of a tree.

• Damage to a tree will be found mid-trunk and higher.

• It can take about five years for a tree to die after being infested.

Residents who have questions about EAB or identifying at-risk ash trees, or concerns about a tree becoming a hazard and if it needs to be removed, can contact Joe Hafner at 218-655-1512 or [email protected]. Property owners can also call the MDA office at 888-545-6684 or report an infestation online at http://www.mda.state.mn.us/eab.

Property owners don't have to resign themselves to losing a beloved ash tree. According to the DNR, injections of insect repellant are recommended for larger trees. Ground-soaking with chemicals can work with smaller trees. Professionals are required for tree injections, while soaking materials can be purchased by property owners. Injection treatments cost $7 to $10 per diameter-inch of the tree. Treatments last for about two years.

As part of the grant process, the city of Cloquet will be creating its own comprehensive website with project updates, educational and informational material for the public. For now, find additional information on emerald ash borer at http://www.mda.state.mn.us/eab.