They’re here

The emerald ash borer has come to Marathon County. Here’s why the destructive little beetle is so scary.


Once upon a time, Dutch elm disease made its way to North America. There were roughly 77 million elm trees in North America prior to the arrival of the deadly fungus around 1930. Spread by a bark beetle, the disease swept across the U.S. and Canada, and by 1989, North America had lost 75% of its elm population. Wisconsin was hit hard. In the early 1950s, Milwaukee lost 16,000 elm trees in a single year to the disease.

Another tree-killing infestation, the emerald ash borer, is currently sweeping across the country. The beetle is now here in Marathon County and will impact the landscape more than Dutch elm disease ever did. County officials made their first official confirmation of the emerald ash borer (EAB) in the town of Rib Mountain in October—on a residential property near Bluegill Bay Park—and expect to soon find many more ash trees infested with the hole-drilling creature. Which means the Wausau area will be seeing lots of dead trees over the next several years.

At first blush, you might think, “Hey, it’s a tree. We have lots of trees here, so no big deal.” But the arrival of the emerald ash borer has far-reaching consequences, both economically and environmentally.

First, ash trees are far more populous in North America than elm trees ever were. When Dutch elm disease devastated urban centers in the U.S. in the 1950s, 60s, and 70s, community foresters turned to the ash tree as one of the main replacements. There are now more than 8 billion ash trees in North America, plus large pockets of native black ash forests in northern Wisconsin, Michigan, and Minnesota.

Because of their hardiness and aesthetics, green and white ash trees have been an urban tree of choice in communities across the Midwest. In Eau Claire, 60% of the urban trees are ash. The 5,000 ash trees make up about 20% of Wausau’s city-owned tree population, but that concentration is much higher in certain neighborhoods.

The area around Riverview Elementary School would be hit hard by EAB. Multiple blocks of Henry Street, Briarwood Avenue, Evergreen Road and Maple Hill Road contain nearly 100% ash trees. Ash trees make up nearly 100% of the street trees on many blocks of the southeast side as well. In many other areas of the city 50% or more of the trees are ash.

That means the way neighborhoods look likely will change dramatically over the next decade. Elm trees that once created lovely canopies over streets and parks were replaced by ash trees, and now these present canopies might disappear in the near future.

“Elm was incredibly overused in urban areas so the impact was great when those elms were lost,” says Wausau/Marathon County Parks & Recreation Director Bill Duncanson. “Ash ironically was used as a replacement tree for elms because it had a similar vase-type shape and was a good urban tree that could withstand urban conditions.”

Many communities didn’t learn the lesson from Dutch elm disease, and put their greenery at risk again by overusing a single species: the ash.

Marathon County isn’t technically yet under quarantine for the EAB, but it might as well be. Wausau/Marathon County Parks & Recreation Forest Administrator Tom Lovlien says the county is working as if it were under the federally-mandated quarantine (it’s just a matter of time before that kicks in).

Ash timber and raw products from Marathon County—including from county-owned property—cannot be transported or sold to non-quarantined areas, except with a special compliance permission from the state Department of Agriculture, Trade, and Consumer Protection. Wood, Waupaca and Portage counties (the emerald ash borer was found in Stevens Point in 2015) are under quarantine, but nearly all northern counties are not.

Furthermore, the cost to county and municipal taxpayers to fight the spread of the pest and deal with dangerous dead trees is significant. Wausau began a $50,000 a year removal and replacement program for urban ash trees in 2017, and beginning in 2019 officials expect to spend $250,000 a year for the next seven years to treat, remove and replace trees.

Wausau Forester Blaine Peterson says neighborhoods full of ash trees will see methodical removal and replacement of existing ash trees—the first being what Peterson calls the “low-hanging fruit,” or trees that are near power lines or need pruning anyway. The idea is that systematic prevention is more cost-efficient than scrambling from one area to the next to take down an infested or dead tree.

The county will spend a considerable amount removing and replacing ash trees near high usage areas such as campgrounds, recreation areas and roads.

Once an ash tree is infested with EAB, it needs to be treated within a year or two, otherwise it dies within four to five years. Even with treatment, the lifespan is questionable. And dead trees deteriorate quickly, creating huge liability concerns.

“It’s about $50 for treatment of an ash tree for two years of life, so $25 a year per tree,” Wausau Alderman Pat Peckham says. Peckham, as the chair of the Parks & Recreation Committee, has been watching the city’s response to EAB closely. “Folks who have been paying attention realize (the EAB) is going to kill everything. I think some people are holding out hope that if they can keep their ash tree that they love on life support for eight years, maybe (researchers) are going to find a way to deal with this.”

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Large taxpayer impact

Marathon County averaged $372,000 in timber sales from 2007-2016. The economic effects of the EAB won’t necessarily be felt in the county’s timber sales. Lovlien says the county works with buyers that already have EAB compliance agreements with the state.

There might be economic consequences of DATCD to companies who have used ash for many years to make products.

Zelazoski Wood Products in Antigo manufactures baseball bats used by Major League Baseball players. The company once used white ash, but not for several years now, says co-owner Ben Zelazoski. Even bigger manufacturers such as Louisville Slugger and Rawlings might have cut back on white ash bats or abandon them altogether due to the havoc the EAB has wreaked on forests in Pennsylvania and New York.

Zelazoski and many other bat producers have switched to maple as their primary choice. That switch so far hasn’t affected the price of maple, but he wouldn’t be surprised if that were to happen in the future.

“Anytime there’s a problem like this it affects other users because if they can’t use the ash then they use other materials, and now there’s more companies looking for the same kind of wood,” Zelazoski says. “Then they start fighting over it because it’s like the last piece of candy in the dish. Maple prices have been pretty stable but it always fluctuates.”

Black ash (sometimes also called “swamp ash”), which grows abundantly in the upper Midwest isn’t typically valued as high-grade lumber and tends to get used for crates and palettes. However, some black ash that grows in drier sites finds its way into veneer and is very expensive.

The cost of EAB on taxpayers could be more harmful than any economic effect it might have on lumber or wood product companies. Wausau is looking at possible costs of nearly $2 million over the next nine years to fight the spread of EAB and deal with removing, treating and replacing sick trees.

Other communities already are feeling the effects of EAB. Since 2009 Milwaukee has been removing some of its 356,000 ash trees—about 24% of that city’s tree population. Burnsville, Minn. a Twin Cities suburb, approved a 10-year, $3.5 million plan in 2013 to fight the EAB. U.S. Forest Service researchers published a study that estimated the cost of fighting EAB from 2009-2019 at $10.7 billion for the removal, replacement and treatment of 17 million ash trees.

This half-inch long insect is going to have a tremendous financial and environmental impact over the next decade.

“We’ve been prioritizing which trees we’re going to save for a while,” Peckham says. “Right now there’s not going to be any saving of the ash trees. We’re going to preserve the life of some for a while.”

Rehabbing forests

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The emerald ash borer was first found in North America in southeast Michigan in 2002, and since has spread to 30 states in the U.S. A species native to Asia, EAB didn’t have much of an effect in its native region as ash trees there had built up tolerances to the beetle and it rarely was lethal. Ash trees in Europe and North America haven’t built up defenses to EAB, and are more prone to fatal infestation.

EAB had been found in 21 of 72 Wisconsin counties in May 2014. Now the beetle has reached 49 counties and it’s only a matter of time before it’s in every county in the state.

The beetle has been creeping north year after year due to many factors, including climate change. Temperatures of minus-30° can kill most emerald ash borers, but it’s been a while since that has happened in Wausau. According to the Wisconsin State Climatology Office, the last time the temperature dipped below minus-30° in Wausau was 1996, and that severe cold has happened only five times since 1970. Even when Wisconsin experienced the polar vortex in the winter of 2013-2014 and had the most days below zero since 1916, the temperature never dipped that low.

“The conventional thought is that EAB is cold weather limited in its northern distribution,” says U.S. Forest Service researcher Brian Palik. “The thought is that the mortality rate for the EAB is high. It’s in logs and under bark. At minus-40 degrees, there’s a really high mortality rate.”

Large tracts of forest also are at risk in Wisconsin—ash trees compose nearly all of the hardwood trees in many areas.

Palik has researched the effects of the EAB in both the Chippewa National Forest in northern Minnesota and the Ottawa National Forest in Northern Michigan. In his studies, Palik has looked at the effects of removing large sections of black ash trees (around four acres) from wetland forests and what potential species could replace them. The results haven’t been entirely positive.

The issue Palik and his research team have run into is finding species that can thrive in a wetland where black ash makes up 90% of the tree population. That’s not so easy. “The sad thing is there aren’t a lot of other tree species that can do well in that setting,” Palik says. “Organizations and agencies need to be proactive in figuring out how to get new tree species established in those wetlands.”

Marathon County already for the past few years has been experimenting with how to regenerate black ash forests. In anticipation of the inevitable, Duncanson and Lovlien have resorted to clear-cutting areas of black ash wetlands, spreading the seeds of multiple tree species they think might work there, and hoping for the best.

“We’ve been seeding with tamarack and other things in those ash stands to try to get something growing. We’re figuring EAB is going to take all of these ash trees out at some point,” Lovlien says. “If we get a good response on tamarack and other species, we’ll go back in the next century and cut the strips and reseed with those. We don’t know what may or may not come back.”

County and city officials have been preparing for the arrival of the EAB for the better part of the decade. Humans are the biggest culprits in spreading the beetle and Marathon County was the first county in the state to prohibit out-of-county firewood into its campgrounds. Duncanson says the county and city have not planted new ash trees since 2004.

Despite the preparation, Lovlien expects to identify more ash trees infected with EAB, likely in campground areas in Kronenwetter Forest, Big Eau Pleine Park, and Dells of the Eau Claire. The recently confirmed EAB infestation in Rib Mountain probably had been there for a few years already.

“Once you have the first find, it’s likely you’re going to have additional finds within the next year,” Lovlien says.

The emerald ash borer is here, and nothing—aside from successive cold snaps that rarely happen anymore—will stop the destructive little beetle.