Years into the emerald ash borer infestation, Sheboygan continues to treat standing trees and recycle dead ones
SHEBOYGAN - On a bleak day just above freezing in March 2016, state officials confirmed the emerald ash borer had infected a tree felled on Ontario Avenue.
It was the first infected tree found in Sheboygan, but the city had been bracing for the infestation for years.
“Suspect emerald ash borer? Look for these signs,” a Sheboygan Press article from 10 years prior advised.
By 2008, the insect was in neighboring counties, and it was discovered elsewhere in Sheboygan County in 2014.
The question for Sheboygan officials at the time was not whether the bug would ravage city’s trees, but rather how to slow the damage to a pace manageable for city workers and budgets.
The plan they landed on has worked out so far, Superintendent of Parks and Forestry Joe Kerlin said.
Sheboygan has now removed half of the approximately 5,000 ash trees that stood along city streets in 2016 and will continue to treat the remaining half with insecticide on a rotating schedule. The felled trees are recycled into mulch.
“It’s done its damage," Kerlin said of the insect. "It’s going to continue to do damage for a while."
The emerald ash borer is a small, green beetle that has killed tens of millions of ash trees since it was introduced to the U.S. from Asia in 2002. Ash borer larvae feed on vascular tissues under the bark, interrupting the flow of nutrients and water and effectively starving infected trees.
Sheboygan slowed the pace of tree deaths, but they will continue
Before the emerald ash borer arrived, ash trees were plentiful across Wisconsin. Nearly one in four trees along streets and in municipal parks in Sheboygan County were ash, according to a public inventory in 2009.
That’s because cities had turned to planting ash trees, which are hardy in urban environments, after the Dutch elm disease similarly wiped out elm trees.
As a result, it was too expensive to simply remove all of Sheboygan’s ash trees when the ash borer infestation hit, Kerlin said.
The city chose to remove half of its ash trees and treat the others — healthier and larger ones.
Some trees that receive treatment (fewer than 10%) do die, but the treatment, which is applied to a tree once every three years, slowed the die-off to prevent the city from getting “stuck with a bunch of dead trees that we couldn’t keep up on,” Kerlin said.
Last year, tree crews removed the last ash tree that was scheduled to be taken down rather than treated.
“We’ll try to preserve what we have,” he said. “When the ash borer has no place to go, I think it might slow down, also. But at some point, there may be no ash trees in the city.
"It is devastating the whole town," he said. "You can drive around and see dead trees in back yards and in the woods out of town."
The path forward is diversifying the city’s tree plantings and trying to replace more trees than are removed, he said.
Recently, the city has been removing more trees than it has been planting. In 2021, for example, the city planted about 470 trees and removed about 670, including 380 ash trees and 290 other dead or hazardous trees, according to the city’s Green Tier sustainability report.
The Sheboygan Restoration of Our Trees (ROOTS) initiative, headed by the Sheboygan Rotary Club and Lakeshore Natural Resource Partnership, is also helping to combat the ash borer and replant trees in Sheboygan County.
More: Sheboygan has revived its Sustainability Task Force. Here's what to know about the relaunch.
Sheboygan is recycling downed trees
While some communities such as Manitowoc and Appleton are selling wood from downed ash trees, in Sheboygan, it is being recycled back to the community.
The branches of all of the removed trees are sent through a chipper — which kills the emerald ash borer — and made into mulch.
The city uses that mulch in places like city parks and also supplies mulch for the community at the recycling drop-off center. The city brings whatever isn't used by the community to a short list of places that will use the mulch and help turn it back into soil, Kerlin said.
The city has also found surrounding businesses and farms willing to take the larger chunk wood that is too big for the chippers and grinders, he said. The city doesn’t end up with many nice logs, but these partners the city has found use it for firewood or sell it.
That’s been more cost-effective than working with the Urban Wood Network, one alternative the city considered, where the city would have to pay for people to come take the wood away, Kerlin said.
“So it’s all being reused, recycled. As long as it’s being used in some way, I feel good about it,” he said. “None of it is going to the landfill.”
Reach Maya Hilty at 920-400-7485 or MHilty@sheboygan.gannett.com.
This article originally appeared on Sheboygan Press: Sheboygan recycles trees infected by emerald ash borer, treats others
