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Phomopsis, Black Knot Easily Found In Winter

Posted on by akabelowsky
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.

Continue reading “Phomopsis, Black Knot Easily Found In Winter” →

Forest Health Specialists Spread The News

Posted on by akabelowsky

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

A DNR group in a forest discusses forest health issues .

Wisconsin DNR Forest Health specialist Bill McNee presents a hazard tree training talk to other DNR workers at Lizard Mound State Park in 2023. / Photo Credit: Wisconsin DNR

Did any of your trees explode during the recent cold snap? Likely not.

Social media — and some traditional news outlets — grabbed hits and headlines by warning folks that the January cold snap could spark a phenomenon they called “exploding trees.”

But Bill McNee, an Oshkosh-based Forest Health specialist for the Wisconsin Department of Natural Resources (DNR), was there to prune the branches of the fast-growing viral story.

Continue reading “Forest Health Specialists Spread The News” →

When Is The Best Time To Prune Trees?

Posted on by janness

By Elton Rogers, DNR Urban Forestry Coordinator
Elton.Rogers@wisconsin.gov or 414-294-8675

To best answer the titular question, I like to start by flipping the question on its head: When is the worst time to prune trees?

To answer this reworded question, we first need to acknowledge that “pruning is wounding.” Anytime you cut off a living portion of a tree, you are doing two main things:

  • Removing photosynthetic material.
  • Creating a potential entry point for decay.

Continue reading “When Is The Best Time To Prune Trees?” →

A New, Intuitive Way To Measure Species Diversity

Posted on by janness

By Dan Buckler, DNR Urban Forest Assessment Specialist
Daniel.Buckler@wisconsin.gov or 608-445-4578

Especially in the wake of emerald ash borer, urban foresters have stressed species diversity as an important goal in the management of local trees. Now there is a new, intuitive way of tracking species diversity by simply counting how many species it takes to make up half of your community’s trees.

This metric is called the top diversity index, or TD-50 index, and was proposed in a 2022 article in Urban Forestry and Urban Greening by Natalie Love and others. The index is deceptively simple — by counting the minimum number of species it takes to comprise 50% of your trees, you have an easy benchmark to improve upon to reduce your reliance on a few species. Continue reading “A New, Intuitive Way To Measure Species Diversity” →

Forest Health Annual Report Hot Off The Presses

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The cover of the 2025 Wisconsin Department of Natural Resources Forest Health Annual Report.

The cover of the 2025 Wisconsin Department of Natural Resources Forest Health Annual Report. / 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 (DNR) has made its 2025 Forest Health Annual Report ready to view and download.

This year’s edition contains 55 pages of reporting on forest health issues throughout Wisconsin, detailing methods employed by the DNR and other agencies to control pests, diseases and invasive plants.

Continue reading “Forest Health Annual Report Hot Off The Presses” →

Hemlock Borer Attacks Stressed Hemlock

Posted on by akabelowsky
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.

Continue reading “Hemlock Borer Attacks Stressed Hemlock” →

Be Mindful Of Invasives During Holiday Clean-Up

Posted on by akabelowsky
A stack of discarded Christmas trees awaits processing at a drop-off facility.

A stack of discarded Christmas trees awaits processing at a drop-off facility. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

Invasive plants and insects don’t mind playing the long game. After all, they’re just trying to survive and thrive, like the rest of us.

They’ll hang out as part of your holiday decorations throughout the season, just on the chance humans might dispose of them improperly, giving them an opportunity to find a new home in your yard or neighborhood.

Continue reading “Be Mindful Of Invasives During Holiday Clean-Up” →

Community Spotlight: Rhinelander — How One Small Community Is Making Urban Forestry A Priority

Posted on by janness

By Tom Jerow, Rhinelander City Forester

View of the same street before and after urban forestry efforts.

The City of Rhinelander, like many communities with populations under 10,000, has struggled to maintain a vibrant urban forestry program. Funding and staffing are its main challenges. The city also faces a variety of urban forestry issues, including pests and diseases, species diversity, community engagement, catastrophic ice storms and aging sewer and water infrastructure. The latter is one of the most significant challenges. Continue reading “Community Spotlight: Rhinelander — How One Small Community Is Making Urban Forestry A Priority” →

Repurpose Your Holiday Tree!

Posted on by janness

By Dan Buckler, DNR Urban Forest Assessment Specialist
Daniel.Buckler@wisconsin.gov or 608-445-4578

To say that working on a Christmas tree farm in high school led me into forestry would be a case of significant historical revisionism. Still, that experience swam in the same waters as reading Lord of the Rings, going on family vacations to the mountains, having a nearby municipal forest and other things that showed me that trees were the way.

Since then, I have increasingly appreciated holiday trees and other green things brought into households, not (just) in the harbinger-of-gifts way, but as reminders of life against a cold, seemingly bleak background. “Things will get better,” these green things announce. “Just wait!” Continue reading “Repurpose Your Holiday Tree!” →