Minnesota cities struggle to stay ahead of emerald ash borer's rapid spread

St. Paul is so busy cutting down ash trees that it can't plant thousands of trees in bare spots across the city. In Woodbury, where the emerald ash borer first appeared in 2017, crews have fallen behind on pruning other tree species on city-owned land.

And in Clearwater, Minn., where an ash borer infestation was found at a truck stop last year, Mayor Andrea Lawrence-Wheeler is searching for volunteers to count the number of ash trees so the city knows the scope of the work ahead.

"I think the answer is, we're kind of on our own," she said.

A decade after it was discovered in Minnesota, the emerald ash borer continues to ravage the urban forest across the state, and 21 counties are now under quarantine. With limited state and federal resources to help communities shoulder the cost of fighting the invasive beetle, local budgets and forestry departments are stretched thin. Many have stopped pruning, planting and maintaining the tree canopy, leaving saplings untended and mature trees vulnerable to storm damage.

"Unless something changes and these communities get the assistance that they need to do all of the work, we're going to see the effects of them having to put off structural pruning and things like that for a significant amount of time," said Valerie McClannahan, urban and community forestry coordinator at the Minnesota Department of Natural Resources. "What the broader effects will be with that have yet to be seen fully in Minnesota."

Minnesota's first documented emerald ash borer infestation was in St. Paul in 2009. It has since spread to the rest of the metro and southeastern Minnesota, as well as a few southwestern counties and Duluth, according to the state Department of Agriculture.

Emerald ash borer larvae chew tunnels beneath the bark, disrupting the flow of nutrients that the trees need to live. Though there are treatment options, such as injecting trees with insecticides, many communities have opted to chop down their ash trees instead.

In St. Paul, ash trees were once a dominant part of the city's leafy canopy. In the past decade, city forestry crews have cut down nearly 15,000 trees along streets and parks.

The city's goal is to remove all ash trees by 2024, and every year, the Parks and Recreation office searches for one-time funds to pay for the work. There are still about 20,000 ash trees to cut down; meanwhile, the department has a backlog of 2,000 resident requests for tree trimming and 13,000 spots that need replanting, and by next year expects to leave behind 950 stumps until it has the time and money to remove them.

Residents along Iglehart Avenue in the Summit-University neighborhood remember when their boulevards were thickly shaded by ash trees. After the trees were cut down months ago, Ula Bukowski was able to see houses across the street for the first time in her seven years on the block.

"We had tons of very large trees, so it's very, very different," Bukowski said.

On Juno Avenue in the Highland Park neighborhood, rows of ash trees became stumps within hours last summer. James Beaumaster, who's lived on his block for five years, said he was relieved when the massive ash tree next to his house came down.

"The trees were starting to die, and I was concerned," he said. "Several of them, if they were to fall, probably would've taken out two or three houses because they were so massive."

Mayor Melvin Carter's proposed 2020 general fund and capital budgets include about $2.3 million for emerald ash borer response, about $600,000 less than this year, when the city stepped in after a state grant ran out. To close the gap, parks will cut back on routine trimming and non-urgent resident requests.

"The response to emerald ash borer is not a discretionary piece of work that the foresters can do," Parks and Recreation Director Mike Hahm told City Council members at a September budget committee meeting. "It's something that is the highest priority for their work, as we have trees that have been identified as dead or dying and need to come down."

It's difficult to estimate the overall cost of the emerald ash borer. In 2009, a study in the journal Ecological Economics estimated the emerald ash borer would cost $10.7 billion over the next decade as the infestation spread from the Midwest. The same researchers estimated Minnesota would spend hundreds of millions of dollars by 2020 — even if foresters managed to stop the pest from spreading.

In Michigan, which in 2002 became the first state attacked by the emerald ash borer, the infestation became "a community-by-community burden" after federal funds dried up, said Kevin Sayers, urban forestry coordinator for the Michigan Department of Natural Resources. He estimated that hundreds of millions of trees have been lost to the invasive pest in both urban and rural areas, and that removal costs have likely reached hundreds of millions of dollars.

In Wisconsin, the emerald ash borer was first identified in 2008 and has since spread across the state. Milwaukee started injecting about 30,000 ash trees with insecticide in 2009 — three years before the beetles were confirmed in the city.

David Sivyer, Milwaukee's forestry services manager, said a three-year treatment cycle costs the city about $100 a tree. Treatment is cheaper than removal and replacement, and the city has been able to keep up with other forestry work, Sivyer said — unlike when Dutch elm disease hit, and regular tree pruning didn't happen for nearly 20 years.

But Sivyer said his city's approach won't necessarily work for everyone.

St. Paul is treating some of its ash trees, but city foresters are focused primarily on cutting down dying trees as quickly as possible. The parks department is applying for grants, including from the state, to supplement the 2020 emerald ash borer budget, Hahm said.

At both the state and federal levels, government aid for emerald ash borer response has historically fallen short of the need, said McClannahan of the Minnesota DNR. In 2018, she said, she got more than 100 applications for a total of $109,000 in grants from the forest service but was able to award four.

In Woodbury, city officials have applied for grants but so far haven't received any, said Public Works Director Mary Hurliman. After the city fell behind on pruning and general maintenance this year, she said, the proposed 2020 budget includes new money for canopy maintenance and a third forester position.

"We're hopeful with these resources that we'll be able to maintain our normal service levels," Hurliman said.

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In Minneapolis, the city levies a tax that pays for emerald ash borer work — but keeping up with stump grinding and routine pruning has still been a challenge, said Ralph Sievert, director of forestry for the city's Park and Recreation Board.

"If you're in certain parts of the city, you can noticeably go, 'Oh yeah, those trees need to be pruned,' " he said.

Surrounded by counties infested by the beetles, Hutchinson, Minn., knows it's a matter of time before its ash trees succumb. So it has cut down between 50 and 100 ash trees a year since 2014, said Donovan Schuette, the town's lone arborist, who started his job in December 2015. City officials have diverted revenue from trash bills into a special fund, which should cover the cost of removing and replacing every ash tree in town, he said.

For now, Schuette said, the city is keeping up. "I'm sure that'll change once it actually gets here," he said.

Emma Nelson • 612-673-4509