Northern WI Forest Health

Green, Sawyer Counties Added To Spongy Moth Quarantine

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Map of Wisconsin showing counties in yellow quarantine for spongy moth.

The updated map of spongy moth quarantined counties in Wisconsin, showing the April 15 addition of Green and Sawyer counties to the quarantined list. / Map Credit: Wisconsin DNR

By Wisconsin DNR

Green and Sawyer counties have become the latest additions to Wisconsin’s spongy moth quarantine, joining most eastern and central Wisconsin counties already considered to be infested by the invasive insect.

The announcement was made April 15 by the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP), based on trapping data collected last year.

Continue reading “Green, Sawyer Counties Added To Spongy Moth Quarantine” →

Forest Health Specialist Paul Cigan Spreads The News

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Paul Cigan (in black hat) discusses the health of a tree with fellow Wisconsin Department of Natural Resources Forest Health specialists Bill McNee and Linda Williams in Cambridge. / Photo Credit: Wisconsin DNR

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

Paul Cigan, the Wisconsin Department of Natural Resources Forest Health specialist for Northwest Wisconsin, has planned a public discussion for Tuesday, June 30, in Ashland.

Cigan will give a presentation on “Invasive Insects and Diseases” and take questions from those in attendance at the event, set for 6 p.m. June 30 at the Northern Great Lakes Visitors Center, 29270 County Hwy. G, Ashland.

Continue reading “Forest Health Specialist Paul Cigan Spreads The News” →

‘Exploding Trees’ Face Long-term Impacts

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A long vertical wound in a tree trunk caused by deep freezing.

Cracked bark and wood creates a long vertical wound typical of the phenomenon commonly called “exploding trees.” / Photo Credit: Wisconsin DNR

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

This past winter, “exploding trees” went viral on social media. Many news outlets followed up with a more realistic explanation of the dramatically named phenomenon, pointing out that while the bitter cold can cause sudden cracks to form on trees, the trees don’t truly explode.

But what happens to those damaged trees as we warm up and move into the growing season?

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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

Look For Spongy Moth Egg Masses And Take Action

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Closeup of a person scraping spongy moth egg masses into a cup.

A putty knife, plastic knife or similar object can be used to gently scrape spongy moth egg masses into a cup of soapy water. The water can be discarded after two days. / Photo Credit: Wisconsin DNR

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

The Wisconsin Department of Natural Resources (DNR) encourages property owners to examine their trees for spongy moth egg masses and determine whether control measures are needed this spring.

Property owners who have oak, birch, crabapple, aspen, willow and linden (basswood) trees should be particularly watchful because the caterpillars of this invasive insect prefer these species. However, they will feed on many other kinds of trees and shrubs.

Continue reading “Look For Spongy Moth Egg Masses And Take Action” →

Thanksgiving Blizzard And Tree Damage

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Ice and snow weigh down trees in a forest after a 2025 blizzard.

Trees bent from the weight of heavy snow following a Thanksgiving-week blizzard in northern Wisconsin. / Photo Credit: Wisconsin DNR

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

This year’s Thanksgiving holiday brought with it not only a hearty meal and a few good hunting stories to tell around the family table, but also a heavy fixing of blizzard-like conditions. The storm caused a real stretch to the proverbial beltline of many trees that were left heavily bent over in its wake.

On the evening of Tuesday, Nov. 25, a potent winter storm moved across northwestern Wisconsin, bringing with it freezing rain that transitioned to heavy, wet snow as temperatures dipped overnight.

Then, on Nov. 28-29, southern Wisconsin experienced its own potent dose of early winter snow when a second large snowstorm moved through, bringing heavy snowfall but with more limited damage.

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Phomopsis, Black Knot Easily Found In Winter

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Phomopsis galls are found on branches of a northern red oak.

This northern red oak has many large Phomopsis galls. / Photo Credit: Wisconsin DNR

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

Winter is a great time to admire the structure of trees. When they are without leaves, you can see how the branches are arranged, how large or small the branches are, and if they are fairly straight or contorted. You might also notice some swellings or growths on those branches.

Two types that can really make a statement are Phomopsis and black knot.

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Hemlock Borer Attacks Stressed Hemlock

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Closeup photo of a hemlock borer larva feeding inside channels in a hemlock tree.

A hemlock borer larva inside channels in a hemlock tree. / Photo Credit: Steven Katovich, Bugwood.org

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

Woodpeckers are often the first to know that a hemlock tree is being attacked by hemlock borer.

Woodpeckers will flake off the outer layers of bark to get at the tasty hemlock borer larvae under the bark, leaving the tree with a reddish hue that, once you’ve seen it, is unmistakable. The woodpecker damage quickly makes it obvious that the tree was fully infested from top to bottom by hemlock borer.

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Shively, McNee To Make Public Appearances

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Tim Shively, the Wisconsin Department of Natural Resources Forest Health specialist for the West Central zone.

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

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

Tim Shively, the Wisconsin Department of Natural Resources (DNR) Forest Health specialist for West Central Wisconsin, will give a presentation titled “Forest Health for Everyone” at a meeting of the Juneau County Men’s Shed at 10 a.m. Tuesday, Jan. 27, in Mauston.

The event is part of a program put on by the Aging and Disability Resource Center of Eagle Country, and will take place at W4890 County Hwy. N, Mauston. It is open to the public. Continue reading “Shively, McNee To Make Public Appearances” →

White Pine Blister Rust Can Devastate Young Stands

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By Tim Shively, DNR Forest Health Specialist
Timothy.Shively@wisconsin.gov or 608-772-6974

A close-up photo of a white pine blister rust canker as seen on a young white pine tree.

A white pine blister rust canker as seen on a young white pine tree. / Photo Credit: Wisconsin DNR

Eastern white pine (Pinus strobus) has historically held great ecological, cultural and economic value throughout Wisconsin, a tradition which continues today. For more than 100 years, however, it has been threatened by a non-native, invasive fungal pathogen called Cronartium ribicola, or white pine blister rust (WPBR).

Continue reading “White Pine Blister Rust Can Devastate Young Stands” →