Emerald Ash Borer Identified in Marshfield

OnFocus -The City of Marshfield Parks and Recreation Department in collaboration with the Wisconsin Department of Natural Resources (DNR) has identified and confirmed Emerald Ash Borer in the City of Marshfield, WI. The insect was identified by City Staff on a private property Green Ash tree and later confirmed by the Wisconsin DNR.

The City of Marshfield has been actively preparing for Emerald Ash Borer by removing ash
trees of concern based on overall quality, size, structure and location. Remaining ash trees
in the parks and streets are actively being treated.

Homeowners who have ash trees on their property are asked to monitor them closely for signs and symptoms of the invasive bug. For those not actively treating their ash tree or planning to treat their ash tree, Emerald Ash Borer has nearly a 100% fatality rate for the infested tree species.

Last year, the City of Marshfield declared May 10-16, 2020 Emerald Ash Borer (EAB) Awareness Week in an attempt to increase knowledge about the devastating impacts this bug can have on ash trees.

Emerald Ash Borer is a harmful insect originating from Asia. Since its discovery in Michigan in 2002, the bug has killed hundreds of millions of ash trees and cost cities, homeowners, nurseries and forest product industries millions of dollars. The bug was discovered in Southeast Wisconsin in 2008 and has since popped up in pockets throughout much of the state.

“Emerald Ash Borer is a looming threat in Central Wisconsin,” said Certified Arborist Luke Haas, owner of Haas Tree Care, LLC. “We’re beginning to see pockets of dead ash trees in the Wisconsin Rapids and Stevens Point areas.”

The bug feeds on ash leaves and causes little damage, but the larvae stage kills the trees by feeding underneath the bark and disrupting the transportation of water and nutrients. Any tree not treated for the bug will eventually die.

“There are a few options when it comes to EAB,” said Haas. “First, we can do a trunk treatment with a certified applicator. There’s several different trunk treatments available; however, Tree-age or Mectinite chemicals have proven to be most effective in combating the invasive pest. These two treatments offer 2 years of protection.”

Haas also said that property owners can undertake a soil drench.

“The chemical Imidacloprid can be applied as a soil drench and can be purchased at nearly every box store or nursery,” he said. “Simply follow the directions on the label for proper application. This treatment offers 1 year of protection and isn’t nearly as effective as the trunk treatments.”

Lastly, property owners can remove the tree.

“If no treatments are done there’s a very high probability that your tree will die, as EAB is a physical beetle that flies around, unlike other common tree diseases as oak wilt or Dutch elm disease,” he said. “To learn more about EAB and treatment options visit emeraldashborer.info or contact a local ISA Certified Arborist!”


  • Spring Time
    • Watch for woodpecker activity on ash trees. Woodpecker will be pecking holes to eat borer in its Pupae stage.Spring and summer
    • Observe for canopy dieback which begins in the upper one-third of the canopy and will progress over time until the tree is bare.
    • What may have been some declining areas last summer would grow into a higher percentage of dieback this summer.
    • Also Epicormic shoots will form, from the roots and trunk, because the nutrients the roots are taking in cannot reach the upper canopy do to xylem damage from S shaped galleries.
    • This is usually visible after some dieback has occurred.Over summer
    • Once the adult beetle has emerged the beetle creates a very distinct D shaped exit hole in the bark.
    • If D shaped holes are visible peel a small area of bark and look for S shaped serpentine galleries.
    • The amount of damage done by EAB will vary depending on the population of EAB in that area.

For more information regarding Emerald Ash Borer and options for your ash trees please,
visit the City’s Forestry web page at:
ci.marshfield.wi.us/departments/forestry/emerald_ash_borer.php. For further
assistance, please contact City Forester Mark Ryskiewicz at 715-486-2073 or Wisconsin
DNR Plant Pest and Disease Specialist, Alex Feltmeyer, at 715-340-3810.

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News Desk
Author: News Desk

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