Emerald Ash Borer in Fairmont

ABOVE: Bark removed from an ash tree at Heritage Acres reveals an s-shaped gallery dug by ash borer larva. This distinctive pattern signals a tree has been infested with the larva.

FAIRMONT- The Minnesota Department of Agriculture (MDA) has recently confirmed the presence of Emerald Ash Borer (EAB) at Heritage Acres in Fairmont. This is the first time Emerald Ash Borer has been found within the city.

EAB is an invasive species of insect lethal to all species of North American ash trees. They can spread by flying short distances or by being transported in infested firewood.

Since they were first discovered in the Minnesota in 2009, EAB has been found in 35 of the state’s 87 counties. The insect has killed hundreds of millions of ash trees in the United States, and Minnesota has over one billion ash trees, the most in the United States.

“EAB is very destructive, it’s going to require a lot of effort to start to tackle all the ash trees in the community, but we knew it was coming,” says Fairmont Director of Public Works and City Engineer Troy Nemmers.

EAB was first detected in Martin County north of Welcome in 2018 and has been close enough to spread to Fairmont for several years. Due to the presence of EAB the MDA has quarantined Martin County, restricting the movement of firewood, ash trees, and ash products.

EAB’s typically take flight between May 1 and September 30. During this period infected trees should not be removed because doing so can spread EAB further.

“If you start tearing (infected trees) apart, all it does is it spreads (EAB) around as you’re hauling and cutting. We’re going to wait until fall to really target that area, and then we’ll start to look at what our plans are (for other trees in town),” said Nemmers.

Ash trees are common in both natural and urban areas. Over 500 ash trees have been planted in Fairmont on public boulevards alone. Now that EAB is in the area, residents should be on the lookout for EAB and consider treating their ash trees to prevent or treat infestation.

Although responding to EAB can be difficult, it can also be more economically feasible than removing and replacing the ash trees it targets.

“If people choose to, if they have a really nice ash tree they want to save, there are treatment options. That’s something that can be done now, and if there are trees that they want to protect, that would be the action they can take now,” said Nemmers.

Adult EAB range from being one third to half an inch long with long slender bodies. They have bright or copper green bodies and a purplish area underneath their wings. Their bodies are the thickest slightly behind their heads.

Ash trees have branches that are typically split directly across from each other. Their compound leaves are composed of five to 11 leaflets. Older ash trees have tight, diamond shaped patterns on their bark, while younger trees have relatively smooth bark.

Once infested with EAB, trees may exhibit a loss of foliage, woodpecker holes from woodpeckers searching for EAB larva, cracking bark, and s-shaped tunnels underneath the bark. Trees may still be saved as long as more than 30 percent of their canopies remain.

If residents believe they have an ash tree which has been infested with EAB, they can contact a tree care professional or the MDA via email at arrest.the.pest@state.umn.us or leave a voicemail at 888-545-6684. Professionals at the MDA can identify photos of EAB and EAB infestations and advise residents how to respond to an infestation.

More information on EAB, how to identify it, how to get trees treated, and advice for homeowners is available at the MDA’s website at www.mda.state.mn.us/eab.


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