Central WI Forest Health

Drought Impacts Young Aspen In North Central Wisconsin

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A portion of an aspen stand showing many leaves dropped due to drought, taken Sept. 2, 2026. / Photo Credit: Wisconsin DNR

By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov, 920-360-0665

Drought impacts can show up abruptly or have a slower impact, with symptoms becoming visible over the next one to two years.

North central and northwestern Wisconsin have faced significant drought conditions over several months this summer.

Continue reading “Drought Impacts Young Aspen In North Central Wisconsin” →

Sapstreak Of Sugar Maple An Oldie But A Goodie

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DNR Forester Paul Etten stands at the base of a sugar maple tree that has small leaves and a thin crown. The tree was dissected and found to have extensive sapwood streaking. / Photo Credit: Wisconsin DNR

By Alex Hornung, DNR Forest Health Specialist, Plover
Alexandra.Hornung@wisconsin.gov

There are some tree diseases that really get a lot of attention and others that get lost in historical documents, only popping up now and again to ignite excitement within the local plant pathologist community.

Maple sapstreak is one of the latter. This year, a site in Shawano County was found to have several trees experiencing symptoms of the disease. The symptoms led to a positive identification of maple sapstreak.

Continue reading “Sapstreak Of Sugar Maple An Oldie But A Goodie” →

White Pine Weevil Also A Problem On Spruce

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Damage to terminal leader of an understory white pine in Portage County. / Photo Credit: Wisconsin DNR

By Alex Hornung, DNR Forest Health specialist, Plover
Alexandra.Hornung@wisconsin.gov

This is a great time of year to be looking for or observing damage from the white pine weevil.

The insect is native and causes terminal leader mortality in susceptible species. Despite the name, there are numerous species of trees that are attacked in addition to white pine, including Norway spruce, jack pine, white spruce and many more.

The damage from white pine weevil is more evident when the needles on the main leader are still attached and are brown in color, primarily in the month of July through the winter of the year that the damage occurred. It is more difficult to see previous years’ damage, because the needles fall off and the dead terminal leader will either snap off or be bare. When the leader is killed, the branches below will grow in place of that leader and will eventually correct by self-selecting a new leader.

Chip cocoons and a larva are found inside the killed terminal leader of a white pine tree. / Photo Credit: Wisconsin DNR

Every year, reports come out of the northern and central zone of damage, sometimes reaching 20% or more in pine/spruce plantings where trees are open-grown. An increased number of reports in plantings have been coming out of the central zone throughout this field season. This may be due to an increase in populations of the weevil this year, or a simple function of thriving plantings that have robust terminal leaders more susceptible to attack.

In forested stands, pesticides are not the primary method of control due to practicality and cost. Trees will very often self-correct, and natural predators will do better when there is an adequate population of the weevil to sustain them. Impacted trees may end up with a noticeable crook in the stem as they continue to grow. These trees can be targeted for removal during regularly scheduled thinnings as the trees mature.

Terminal leader damage is evident on planted white pine and spruce trees in Waushara County. / Photo Credit: Wisconsin DNR

For more information about white pine weevil in Wisconsin, please refer to this article from 2023, written by Linda Williams, Wisconsin Department of Natural Resources Forest Health specialist for the Northeast zone.

Forest Health Specialists Plan Appearances

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Tim Shively, Wisconsin DNR Forest Health specialist for the West Central zone.

Tim Shively, Wisconsin DNR Forest Health specialist for the West Central zone. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

A list of public appearances planned by Wisconsin Department of Natural Resources (DNR) Forest Health specialists over the coming weeks:

  • Tim Shively, DNR Forest Health specialist for the West Central zone, will present a forest health overview tailored for landowners, land managers and volunteers at a meeting of the Chippewa County Land Conservancy, set for 6:30 p.m. Tuesday, April 14, at Lafayette Town Hall, 5765 197th Street, Chippewa Falls
  • Linda Williams, DNR Forest Health specialist for the Northeast zone, will present a forest health overview to loggers, truckers and foresters at the 21st annual Sustainable Forestry Conference, set for Wednesday, April 15, inside the ski lodge at the Keyes Park Recreation Area, 4960 County Hwy. 101, Florence. Registration is required. More event information can be found on the University of Wisconsin-Madison Extension website.
Linda Williams, DNR Forest Health Specialist for the Northeast Zone, addresses forestry workers.

Linda Williams (left), DNR Forest Health specialist for the Northeast zone, addresses workers during a forestry seminar. / Photo Credit: Wisconsin DNR

Forest Health Specialists Plan Public Talks

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

Photo showing Wisconsin Department of Natural Resources Forest Health specialists (from left) Bill McNee, Paul Cigan and Linda Williams discuss a tree during the Cambridge Tree Tour in July 2025.

Wisconsin Department of Natural Resources Forest Health specialists (from left) Bill McNee, Paul Cigan and Linda Williams discuss a tree during the Cambridge Tree Tour in July 2025. / Photo Credit: Wisconsin DNR

Two Wisconsin Department of Natural Resources (DNR) Forest Health specialists will give presentations that are open to the public in the coming weeks:

  • Thursday, Aug. 7: Alex Hornung, Wisconsin DNR Forest Health specialist for central Wisconsin, will discuss the DNR’s Forestry program at Farm Technology Days. The event will run from noon to 5 p.m. at Clinton Farms, E8351 State Hwy 22, Bear Creek (Waupaca County). Admission is $15 per adult.
  • Friday, Sept. 5: Paul Cigan, DNR Forest Health specialist for northwest Wisconsin, will give a presentation on “Fungal Pathogens of the Wisconsin Forest” as part of the Wisconsin Mycological Society’s “Northwoods Foray” in Cable (Bayfield County). Cigan’s talk will run from 7:30 to 8:30 p.m. The Northwoods Foray will run from Sept. 4-7. Those interested in attending can visit the event’s webpage to obtain more information and sign up for a fee.

Jack Pine Budworm Outbreak Subsides

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By Paul Cigan, DNR Forest Health Specialist, Hayward
Paul.Cigan@wisconsin.gov or 715-416-4920

Aerial view of jack pine budworm defoliation in jack pine stands in Douglas County during the 2023 outbreak. / Photo Credit: Paul Cigan, Wisconsin DNR

Jack pine defoliation caused by the jack pine budworm (JPBW) continued at mostly light levels this year, affecting stands in the Central and Northwest Sands Ecological Regions of Wisconsin.

In the Northwest Sands, jack pine stands experienced light and scattered defoliation across Burnett, Douglas, Polk and Washburn counties. In the Central Sands, JPBW caused moderate to heavy defoliation across roughly 500 acres of jack pine on county and state forests in Jackson County, east of Black River Falls.

Continue reading “Jack Pine Budworm Outbreak Subsides” →

Weather Whiplash Affects Pine Stands

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Swath of dead pine due to high water table mortality

A swath of pine dead due to high water table mortality in 2020 in northeast Wisconsin.

By Alex Hornung, DNR Forest Health Specialist, Plover;
Alexandra.Hornung@wisconsin.gov

Many pine stands across central and northeast Wisconsin are being impacted by the change from high levels of precipitation to extreme drought that has occurred over the last 5-7 years.

Drastic or sudden changes can be particularly stressful to trees of all species, but especially to pine stands that prefer well-drained soil types.

Continue reading “Weather Whiplash Affects Pine Stands” →

Watch For Spongy Moth Caterpillar Diseases

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By Bill McNee, DNR Forest Health Specialist, Oshkosh
Bill.McNee@wisconsin.gov or 920-360-0942

With this spring’s weather bringing above-average rainfall across most of Wisconsin, we will likely see moderate to heavy mortality of spongy moth caterpillars at many locations this summer.

Last year, the statewide May-June period was the third-driest since recordkeeping began in the late 1800s, according to the NOAA National Centers for Environmental Information. As a result, the effectiveness of the caterpillar-killing fungus, Entomophaga maimaiga, was limited. Spring 2024 is noticeably wetter, and thus, increased effectiveness of E. maimaiga is likely.

Continue reading “Watch For Spongy Moth Caterpillar Diseases” →

Woodpecker Damage On Ash Trees May Indicate Emerald Ash Borer

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By Bill McNee; DNR Forest Health specialist, Oshkosh;
Bill.McNee@wisconsin.gov or 920-360-0942

Photo showing woodpecker damage on an ash tree trunk, an early sign the tree might be infested with emerald ash borer.

Woodpecker damage is an early sign an ash tree might be infested with emerald ash borer. / Photo Credit: Wisconsin DNR

The Wisconsin Department of Natural Resources (DNR) encourages property owners to watch for woodpecker damage to their ash trees this winter. If damage is found, property owners should make plans to take action in the spring.

Woodpecker damage, often called “flecking,” happens when birds peck away some of a tree’s bark to access the larvae underneath. Flecking is a common early sign that an ash tree might be infested with emerald ash borer (EAB), an invasive insect. EAB is the most damaging threat to Wisconsin trees, killing more than 99% of the untreated ash trees it infests.

Continue reading “Woodpecker Damage On Ash Trees May Indicate Emerald Ash Borer” →

Forest Health Forecast For 2024

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Paul Cigan, DNR Forest Health Specialist, Hayward;
Paul.Cigan@wisconsin.gov or 715-416-4920

An aerial photo of oak and aspen forests showing heavy defoliation from spongy moth.

Oak and aspen forests with heavy defoliation from spongy moth. Additional defoliation coupled with ongoing drought in the upcoming 2024 growing season is expected to put significant stress on affected forests. / Photo Credit: Paul Cigan, Wisconsin DNR

Maintaining a healthy and productive forest often requires — more than ever before — a working knowledge of how to anticipate, prevent and mitigate environmental stressors that threaten to undermine it. The list of stressors includes drought, impact of forest insects and diseases.

In a recent and timely article, Denise Thornton of My Wisconsin Woods taps the expansive knowledge of the DNR’s Forest Health team and a state climatologist to bring focus to the threats facing forests this year.

She also lists steps that can be taken to ensure health and proactivity are maintained in your forests.