Local war against ash borer escalates after tree-killing pest found in Moorhead

Moorhead and Fargo are gearing up for a lengthy fight against a pest infamous for decimating ash trees. The insect has not been detected in Fargo, but officials believe its arrival is inevitable.

Moorhead arborist Mike Odegaard cuts down an ash tree on Wednesday, March 15, 2023, in the 1100 block of 30th Street South in Moorhead. Crews are working to remove some ash trees after the emerald ash borer, an invasive pest that kills ash trees, was detected in the city in February.
Alyssa Goelzer/The Forum

MOORHEAD — A forestry crew was busy removing ash trees along a south-side boulevard this week in an effort to slow the potentially devastating impact of the emerald ash borer, an invasive beetle that recently darkened Moorhead’s doorstep .

In preparation for the tree cutting, foresters went through the residential neighborhood along the 1100 block of 30th Street South in Moorhead and left an orange X on all the trees slated for the ax.

“We’re a little disappointed because we don’t have many trees in the area,” said Katy Enkers, a nearby resident.

Jeff Hilde, another neighborhood homeowner, understands the necessity of removing the trees.

Ash trees around the 1100 block of 30th Street South in Moorhead were marked with an orange X to let forestry crews know which trees to cut down in the city's battle against the emerald ash borer on Wednesday, March 15, 2023.
Alyssa Goelzer/The Forum

However, it was still sad, Hilde said, when the foresters came through the neighborhood on Wednesday, March 15, because, after years of waiting, the trees were finally getting big enough to be enjoyable.


The forestry crew made short work of digging out, cutting down and hauling away roughly a dozen trees.

“We will be back in the summer to grind the stumps (in the neighborhood) and plan to install new trees in the fall,” said Moorhead City Forester Trent Wise.

In the coming years his team will have to repeat this process for roughly 1,700 ash trees throughout Moorhead to try to slow the ash borer down.

Both Moorhead and Fargo are gearing up for a lengthy fight against a pest infamous for decimating ash tree populations. The insect has not been detected in Fargo, but officials believe its arrival is inevitable.

A Moorhead forestry crew removes an ash tree that was cut down in the city's fight against the emerald ash borer on Wednesday, March 15, 2023, in the 1100 block of 30th Street South.
Alyssa Goelzer/The Forum

The city of Moorhead is cutting down smaller ash trees to slow the spread of the ash borer in an attempt to save some of their more mature ash trees. “The fewer hosts we have in the city, the less chance the population will build up,” Wise said.

Elsewhere in Minnesota, the insect has been wreaking havoc for years.

One Twin Cities suburb has tried several innovative solutions to slow the borers’ spread, while the lake-side city of Duluth has nearly given up on their ash trees after years of bombardment.

With the insects' recent arrival in Moorhead, city foresters are left scrambling to complete a huge amount of work as quickly as possible to mitigate the impact of this destructive pest.


“We’re as prepared as we can be,” Wise said, but now that it has arrived they have a lot to do.

An emerald ash borer beetle on a green leaf. Thinkstock / Special to The Forum
Adult emerald ash borers are bright metallic green and about 0.33 inches long.
Thinkstock / Special to The Forum

Moorhead has 6,800 ash trees on public property within the city. Its goal is to treat 4,000 of these over the next three years by injecting a chemical into their trunks, with the hope of repelling ash borers.

The rest of the city's ash trees, including those with trunks less than 10 inches in diameter and damaged trees, will be removed and replaced with different types of trees, according to Wise.

Officials in Moorhead and Fargo recommend that residents who have ash trees on their property make a plan now. They can choose to treat the tree against the ash borer or have it removed.

“Once those trees become infested they become very brittle and very hazardous,” Wise said, “and can become more expensive to remove.”

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Fargo arborists on high alert

The ash borer has slowly made its way west across the country by hitching a ride on firewood. The beetle, native to Asia, has killed hundreds of millions of ash trees throughout 36 states since it was first discovered in the U.S. in 2002.

Assuming it’s only a matter of time until the pest is found in Fargo, the city's forestry division has replaced more than 3,600 boulevard ash trees since 2012, reducing the ash population to less than 24% of the city's tree inventory. How the ash borer's arrival in Moorhead will change Fargo's approach, if at all, is unclear. A representative from Fargo's forestry division was unavailable for comment in time for publication.


In coordination with the city, the Fargo Park District is acting now so it has a head start on the insect.

“Ultimately we’re in a pretty good position,” said Fargo Park District Forester Sam DeMarais. “We’ve really had a good opportunity to see what was coming and get well ahead of this pest.”

“If you do nothing, the emerald ash borer can really ramp up its population,” DeMarais said.

The park district plans to cut down 1,000 of the 3,500 ash trees in Fargo’s parks over the next three years. The trees removed will all be less than 8 inches in diameter, or damaged, DeMarais said. Another 1,000 trees will be left untouched for now and will be removed if they are infected, he said.

The remaining 1,500 trees in Fargo’s parks will be treated, he said. It will cost about $2 million over the next 20 years to treat and sustain these ash trees, DeMarais estimates. However, the cost to remove and replace all these trees would be far more.

Maplewood, Minnesota, a Twin Cities suburb similar in population size to Moorhead, has been dealing with the effects of the ash borer since 2017, and the problem has only intensified.
“Right now it is a lot to handle,” said Maplewood’s Natural Resources Coordinator Carole Gernes. “It’s just everywhere in Maplewood.”

They, too, started out by purging ash trees from affected areas and cutting down already damaged trees.

Last year Maplewood began treating specific ash trees on city property with the aim of saving them, and crews continue to remove weakened trees in an effort to keep up with the infestation.


Maplewood has also pursued innovative solutions that Gernes said could be a good fit for the city of Moorhead.

Emerald Ash Borer.jpg
An ash borer tunnel, called a gallery, is made by larvae feeding on the tree. Once this happens, the tree dies within one to three years, according to Minnesota officials. This makes the tree very brittle, prone to breaking and difficult to take down.
Minnesota Department of Agriculture photo

A species of tree wasp that enjoys feasting on ash borer larvae was released in an infected area in Maplewood, Gernes said, as part of a partnership with the Minnesota Department of Agriculture.

In addition, Maplewood has partnered with a local nonprofit to sell trees for $40 to help residents replace ash trees on private property.

In Duluth, Minnesota, city officials have thrown up their hands in the fight against the ash borer. Their city council decided in February to give up much of their treatment efforts and prioritize cutting trees down quickly as the beetle is overwhelming the city .

“We’re constantly trying to keep up with it,” Duluth’s City Forester Clark Christenson told the Duluth News Tribune in February. “We’ve sort of let stump grinding go by the wayside, because stumps don’t fall on people.”

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