Woodland owners

After A Quiet Year, Conduct Spongy Moth Egg Mass Surveys This Fall

The only mature spongy moth caterpillar detected at Harrington Beach State Park in Ozaukee County in July 2026 crawls up a tree’s mainstream. / Photo Credit: Wisconsin DNR

By Bill McNee, DNR Forest Health Specialist, Oshkosh
Bill.McNee@wisconsin.gov

Wisconsin’s recent period of high spongy moth (Lymantria dispar) populations came to an end in 2025 and the population remained very low in 2026.

Only a handful of caterpillar reports were received, most often coming from southern Jefferson County and eastern Dane County. Most notably, numerous bur oaks were reported to be infested with several hundred caterpillars per tree in and around Cambridge, Fort Atkinson and Lake Mills; light feeding damage was visible.

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Free Hemlock Woolly Adelgid Survey Training Opportunity

Mitch Lannan of the Wisconsin Department of Agriculture, Trade and Consumer Protection, shows a hemlock branch infected by hemlock woolly adelgid. / Photo Credit: Wisconsin DATCP

By Wisconsin Department of Agriculture, Trade and Consumer Protection

Are you interested in learning how to help protect the health of Wisconsin’s hemlocks? A new interactive opportunity is being offered this fall by the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) to monitor for hemlock woolly adelgid (HWA).

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Autumn Is A Great Time To Treat Invasive Plants

A nonnative honeysuckle plant with berries. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

As temperatures begin to decline, the leaves of many plants and trees have begun to change color. Some trees in the northern part of the state have already begun dropping leaves.

The Wisconsin Department of Natural Resources (DNR) reminds the public that in addition to enjoying the changing hues in the woods, fall also presents a great opportunity to spot invasive plants.

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Forest Health Team Debuts Two New Fact Sheets

An image of the front page of a DNR fact sheet.

The front page of the Wisconsin DNR’s new Forest Health Fact Sheet on oak decline. / Graphic Credit: Wisconsin DNR

By Art Kabelowsky, DNR Outreach and Communications, Fitchburg
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

The Wisconsin Department of Natural Resources Forest Health team has published two new fact sheets, bringing the total count of its fact sheet offerings to 26.

The new fact sheets:

  • Fall Webworm: DNR Publication FR-622u discusses basic information on the biology of the insect (Hyphantria cunea), its life cycle, potential lookalike caterpillars and management options.
  • Oak Decline: DNR Publication FR-622v covers the tricky topic of oak decline, which is not caused by one distinct forest pest or problem but instead is the result of multiple factors — some predisposing, some inciting and some contributing — that work in combination to cause decline.

The fact sheets are designed in full color, with photos, and are meant to be printed out for reference or to carry into the field. They can also be viewed online. They can be printed on standard letter-sized paper. Most fact sheets are two pages, meant for two-sided printing; a few are four-page documents.

A complete directory of links to all DNR Forest Health fact sheets is available online.

Oak Decline May Continue In 2026

A wide view of declining oak trees following spongy moth defoliation and drought.

Oak trees with thin canopies experiencing decline following spongy moth defoliation and drought in the prior few years. / Photo Credit: Wisconsin DNR

By River Mathieu, DNR Forest Health Specialist, Fitchburg
River.Mathieu@wisconsin.gov

Oak decline is a complicated forest health issue impacting oak forests in Wisconsin.

In the past few years, oak decline has been recorded in several regions of Wisconsin, primarily linked to spongy moth defoliation and drought conditions that occurred from 2022-2024.

As the summer months of 2026 continue to unfold, oak decline may continue in areas previously impacted by spongy moth and drought.

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Species Spotlight: Red Hailstone

A large creeping vine blankets neighboring trees and plants.

A red hailstone infestation in Dane County blankets surrounding vegetation and can be seen climbing into trees. / Photo Credit: Wisconsin DNR

By Carter Hellenbrand, DNR Invasive Plant Field Specialist, Fitchburg
Carter.Hellenbrand@wisconsin.gov

Note: This is the third installment in the Forest Health News “Invasives Spotlight” series, a series of articles released monthly during the growing season.

What is heart-shaped and hairy all over? Red hailstone!

Two hands holding tubers of the red hailstone plant.

Underground tubers of red hailstone. The tubers easily break off to create new plants. / Photo Credit: Wisconsin DNR

Also known as golden creeper or Manchu tubergourd (Thladiantha dubia), this invasive perennial vine can grow 18 feet in a single growing season and spreads through underground potato-like tubers that break off from the root system to create new populations.

 

 

 

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Cooperative Enlists Public To Make Tree Health A Snap

A worker speaks with colleagues in a forested area.

Dr. Scott O’Donnell, center, a forest geneticist with the Wisconsin Department of Natural Resources Forest Economics and Ecology section, updates members of the DNR Forest Health team on upcoming genetic projects at an orchard near Lake Tomahawk in Hazelhurst during the Forest Health team’s summer meeting on May 25, 2024. / Photo Credit: Wisconsin DNR

By Art Kabelowsky, DNR Outreach and Communications, Fitchburg
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

It takes more than a village to foster healthy forests. More than a township, a city and a county, too. Sometimes, even more than a state.

That’s why the Great Lakes Basin Forest Health Cooperative (GLB FHC) was formed five years ago by Holden Arboretum in Ohio and the U.S. Department of Agriculture Forest Service.

Geographically, the group’s region encompasses an area from New Jersey to Wisconsin. The Wisconsin Department of Natural Resources (DNR) is an active member.

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Watch for Asian Longhorned Beetle

Closeup of an insect crawling on a person's hand.

An adult Asian longhorned beetle. / Photo Credit: Wisconsin DNR

By Michael Hillstrom, DNR Invasive Forest Pest Coordinator, Fitchburg
Michael.Hillstrom@wisconsin.gov or 608-513-7690

Asian longhorned beetle (ALB) has not been found in Wisconsin, but early detection is critical to eliminating it from infested areas. Forest Health workers from Wisconsin, Michigan, Minnesota and Manitoba, Canada, recently had the opportunity to visit an active ALB infestation in South Carolina to learn how to identify infested trees. This experience will greatly enhance staff’s ability to detect ALB and respond rapidly.

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New Program Connects Hunting Heritage With Landowner Forest Management

Photo of a young deer wanders through a woodlot with invasive plants.

A young deer wanders through a woodlot with invasive plants. / Photo Credit: Central Pennsylvania Forestry blog

By Bob Nack, DNR R3 Supervisor, Madison;
Robert.Nack@wisconsin.gov or 608-617-3492

A joint state-landowner program proven successful in Wisconsin areas is under consideration for expansion into more counties to combat the slow, but steady decline in active deer hunters, prompting concerns in both environmental and economic realms.

The program, also tested successfully in other states, requires participants to complete hunter education safety and online deer hunting 101 courses. Participants also are required to practice at the shooting range and join in live virtual meetings. Experienced mentors are ready to provide guidance and support to participants.

Adams County landowner Matt Dettlaff endorsed the program. “Our landowner cooperative recognized this program as another valuable new tool in our herd management toolbox,” he said.

Forest landowners, including Dettlaff, see the browsing impact high deer densities can have on tree regeneration and wildlife-habitat quality. One strategy of this program is to tap new adult hunters to harvest antlerless deer for specific property goals. Landowner participants would determine the antlerless harvest goals and control the hunting plans for their properties.

“We typically cannot harvest enough antlerless deer ourselves to meet our goals to keep the herd in balance with quality habitat,” Dettlaff said. “Helping introduce new folks to the deer hunting tradition we are passionate about is just an added feel-good bonus.” Check out this video from the 2025 late-season firearm hunt in Adams County.

Landowners passionate about forest management and the future of deer hunting are encouraged to participate in any of these ways:

Organized late-season firearm hunt for antlerless only: An organized firearm antlerless deer hunt in early December. Program includes an evening social and a deer-processing demonstration. Ideally, a landowner or group of area landowners provide hunting opportunities for at least 10 adult hunters. Landowners identify antlerless deer harvest goals for their property.
Archery hunting: The DNR contracts with Raised at Full Draw (RAFD) to provide archery educational programs. RAFD is piloting a Field to Fork bow hunting program for adults. Participants commit to attend weekly archery practices from June through August. Participants  are also expected to complete weekly homework online to review at in-person meetings. Before hunting, an archery shooting proficiency test will be administered by instructors to ensure participants have mastered their equipment to hunt ethically. RAFD is looking for landowners with property within an hour of Madison.

Interested? Contact Bob Nack, DNR R3 Supervisor, at Robert.Nack@wisconsin.gov or 608-617-3492.

Spring Weather Damages Trees

Red pine damaged by the April 2nd, 2026, ice storm in central Wisconsin. / Photo Credit: Wisconsin DNR

By Michael Hillstrom, DNR Invasive Forest Pest Coordinator, Fitchburg
Michael.Hillstrom@wisconsin.gov or 608-513-7690

Spring 2026 has seen a variety of tree stress events. Wisconsin trees have experienced snow and ice damage, severe storms that resulted in wind, hail and flood damage and swings in temperatures that brought leaf out and subsequent frost damage.

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