Tuesday, October 16, 2018

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Ash borer has arrived in Eau Claire

Eau Claire joins 47 other state counties under quarantine for the tree-killing bug

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    The emerald ash borer is a tree-killing beetle found recently in Eau Claire.

    Contributed photo

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    City arborist Josh Rasmussen ground an ash tree stump on March 30 in Eau Claire. For about five years, the city has been removing ash trees before the emerald ash borer’s anticipated arrival in Eau Claire. The tree-killing bug was discovered last week in trees on the UW-Eau Claire campus.

    Staff file photo

  • Todd-Chwala-Eau-Claire-city-forester


    Contributed photo

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    Contributed photo

Eau Claire County became part of Wisconsin’s quarantine zone on Monday for a beetle that kills ash trees.

Residents can no longer transport firewood, and homeowners with an ash tree in their yard should weigh measures for staving off the emerald ash borer.

Eau Claire city arborist Lucas Stelter recently spotted an ash tree that suffered heavy woodpecker damage on the UW-Eau Claire campus near Water Street. The birds were feasting on ash borer larvae, which ate their way through the tree’s vascular system, cutting off the flow of water and nutrients to limbs.

“This insect has likely been in this particular tree for quite some time,” Todd Chwala, manager of the city’s parks, forestry and cemetery division, said in a statement.

Additional nearby ash trees also exhibited signs of ash borer infestation. State Department of Natural Resources workers collected larvae from the trees last week. Tests confirmed they are ash borers — the first confirmed sighting of them in the city and Eau Claire County.

The state Department of Agriculture, Trade and Consumer Protection added Eau Claire County to its ash borer quarantine zone, which already had 47 other counties, including neighboring Chippewa, Jackson, Buffalo and Trempealeau.

Based on the way the bug has spread across the state, DATCP believes it is getting help from people.

“Although we have now found EAB in 48 counties, much of the area in those counties remains uninfested. These scattered infestations are caused by human activity, not natural spread of the insect,” Brian Kuhn, director of DATCP’s Plant Industry Bureau, said in statement. “So, it’s still important for people not to move firewood out of infested areas, even within their own quarantined counties.”

Residents who do chop down ash trees can burn the wood in a fireplace or backyard fire pit, get it chipped into pieces no bigger than a half-inch or store logs under a tarp until they can be properly disposed.

Backyard trees

For those with ash trees in their yards, there are pesticides available to deter the beetles from infesting them and mitigate damage for those that already have minor infections.

“There are some preventative treatments that can be done for ash trees,” said Erin LaFaive, horticulture educator for the UW-Extension office in Eau Claire County.

Applying those pesticides around the base of the ash tree must be done on an annual basis to keep the bugs at bay.

“You have to balance if it’s worth saving, if it’s worth pre-treating,” LaFaive said.

And for larger ash trees, homeowners are advised to consult a certified arborist as opposed to applying pesticides themselves.

With the ongoing costs of pesticide treatments, residents may want to consider planting different varieties of trees in their yard with the expectation their ash trees will eventually die.

“People can start thinking about planting other trees,” LaFaive said.

For ash trees with more than half their canopies gone from ash borers, UW-Extension recommends removing them.

Signs of ash borer infestation include thinning or dying branches in the upper canopy, woodpecker activity, S-shaped feeding patterns underneath dead bark, D-shaped exit holes created by the adult insects, and water sprouts along the trunk and large branches.

Another warning sign is ash trees putting up new sprouts at their base, which is a sign the tree is stressed and desperately trying to create new growth, LaFaive said.

Trees hang on for a few years after they’re first infested, but it’s often too late for them by the time people spot the effects of the bug.

“They die fast, and they dry out really fast,” LaFaive said.

Trees severely impacted and dying from the emerald ash borer become weak and the potential for branches breaking poses a danger to people and property.

Ready for it

Aware of the emerald ash borer’s impending arrival, the city of Eau Claire put a proactive management plan into action about five years ago.

At the time, ash trees accounted for almost a third of the trees on city property. Since then, the city has removed more than 2,500 ash trees, replacing them with other species for a more diverse urban canopy to better weather pests that target specific varieties. Ash trees now account for about 18 percent of the urban forest in Eau Claire, according to Chwala.

The emerald ash borer management plan is ongoing and is part of the approved 2018 budget. With the confirmed sighting of the bug, Chwala said, the city will be closely evaluating its budget needs for 2019.

The ash borer, which is native to China, is believed to have entered the U.S. on packing material, first showing up in 2002 in Michigan. The bug was first seen in Wisconsin during 2008 in Washington County.

Contact: 715-833-9204, andrew.dowd@ecpc.com, @ADowd_LT on Twitter

MORE INFO: Go to labs.russell.wisc.edu/​eab and datcpservices.wisconsin.gov/​eab for ways to identify infected trees, track the bug’s spread across the state and methods for treating ash trees.

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