Time running out for ash trees as emerald ash borer on rapid uptick in Fond du Lac County

FOND DU LAC COUNTY – If you want to save your ash tree, now may be the last opportunity to do so.

This is the message Wisconsin Department of Natural Resources Forest Hall Specialist for Southeast Wisconsin Bill McNee has for Fond du Lac County residents as a “rapid decline” of the tree species is seen around the county, thanks to the emerald ash borer infestation.

Small bug, large impact 

The beetle came to the United States in the 1980s and 1990s, most likely through imports from China, but were not identified in the country until 2002, McNee said.

As its name states, the borers infest ash trees. According to department’s website, adult bugs, metallic green in color and the size of “a cooked grain of rice,” lay their eggs in the crevices of the bark. Once they hatch, the larvae then chew into the bark and develop underneath it. Until they are adults, the bugs cannot be seen unless the bark is removed from the tree, according to the department. 

When wood, nursery stock and logs moved across the United States, the bugs hitched a ride and spread across the nation. In 2013, the bug was first found in Fond du Lac County at Mauthe Lake. In 2015, the city of Fond du Lac noticed the infestation, although they were “most likely present several years earlier,” said McNee.

The city was the first place “widespread decline” was seen in the county, said McNee, and today many trees have been treated or removed. As the beetle descended on Fond du Lac, the city responded by "preemptively removing" trees, and treating others, said Director of Public Works Jordan Skiff at a recent city council meeting. Although a large number of ash trees are showing the effects of infestation, these moves have helped to keep it manageable in comparison to other communities reaching "crisis levels," he said. 

In North Fond du Lac, the beetle was also first identified in 2015, and in 2016, the village began removing trees affected, said Village of North Fond du Lac Director of Public Works Darrin Parsons. This practice of only removing the worst carried into 2017, and as of this year, 226 trees have been removed, with 260 along streets and parks affected by the emerald ash borer still waiting to be removed, he said. 

Throughout the rest of the county, the infestation has rapidly increased, with 30 to 50 percent of the county’s canopy in decline. In areas like Mount Calvary, St. Cloud, Campbellsport, Ripon, Waupun, Alto and Brandon, ash trees are either dead or declining, he said.

Department employees hoped this past winter’s polar vortex would kill the bugs and slow the infestation. Instead, they found the bugs protected under the bark, well adapted to the weather and set for the continuation of rapid growth, McNee said.

Beetles produce 40 to 200 eggs each, and can fly for miles, allowing the infestation to spread over distances.

“Even if you lose 80 percent, you still have a very good population,” said McNee.

While last year confined to regions of the county, this year they are everywhere, he said.

Typically, McNee will see one to two bugs on an inspected tree. This summer, from two trees in Mount Calvary, he pulled off more than a dozen — one the highest amounts he's ever taken at once.

“(The presence of borers isn't) a new thing in Fond du Lac County,” said McNee. “The increasing abundance and rapid tree mortality is relatively new.”

To help keep the bugs at bay, “several natural enemies from Eastern Asia,” including wasps, have been imported to help newly planted trees reach reproductive age. The wasps do not sting people, but attack the larvae and eggs, said McNee.

Clock running down on saving trees

As bigger trees are at risk, everyone in the county should assume any ash tree they have has been infested at some level by the bug, said McNee. The only tree spared is the Mountain Ash, as it is not a “true” ash tree, he said. 

Homeowners have two options: either treat the trees or tear them down. When doing the former, McNee recommends moving as quickly as possible as typically trees do not show signs of infestation for a few years, and those left untreated can die within the same time frame.

To treat a tree, homeowners should call an arborist for advice on how to best do so. A list of contacts can be found on the Wisconsin Arborist Association’s website. Insecticides can be applied by homeowners and is typically drenched around the tree, injected into the soil or into the tree itself, McNee said.

Treatment is done every one to two years throughout the life of the tree. While people may think this could make it more costly than tearing the tree down, treatment could be less or equal to the cost of removal, he said.

Not all trees should be treated, however, such as those under power lines, sending roots into driveways or in other bad spots. Those that should be saved are those that “add benefit to the property,” he said.  

When replanting trees, he recommends home and wood lot owners plant a diverse mix of trees.

Those with wooded lots are encouraged to act quickly, as well. Wood from the county is used to make wood pulp and saw timber, but if the tree is infested, it can become too dry and its value becomes little to none, said McNee. To be able to “salvage the economic value” of the trees, he recommends working with a professional forester to engage in soil conversation and grow trees needed for production.

The department’s website offers a directory that includes foresters. The department’s foresters will walk through wooded lots for free with the owners to advise them on management, said McNee. Owners can also contact Field Forester Tom Vanden Elzen at 920-312-6128.

If neither is done, by next year it will most likely be too late, said McNee. When in decline, trees become dry and brittle. This can create a legal liability, as the tree can snap and fall onto homes, cars and people. In October 2018, a woman in Racine was killed when an infested tree slated to be cut down blew over in high winds and crashed onto her car, according to CBS 58.

“Getting in there early and acting is beneficial for you. You can treat the tree while it’s not infested or lightly infested, or get into the forest and manage the forest and capture the financial value from the timber while it still alive and healthy,” he said.

Want more information on protecting your ash tree from emerald ash borers?

Visit the Wisconsin Department of Natural Resource's website, dnr.wi.gov, for information in the bug. To find an arborist, visit the Wisconsin Arborist Association website at waa-isa.org. To learn more about ash trees and how to identify them, visit the University of Wisconsin-Madison's website at labs.russell.wisc.edu/eab/what-is-an-ash-tree.

Contact Sarah Razner at 920-907-7909 or srazner@gannett.com. Follow her on Twitter @misssarahrazner. 

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