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Spring Brings Opportunities To Protect Oak Trees

A photo of an oak tree with a branch that has been pruned, but not treated with protective paint to prevent infection with oak wilt.

Pruning, cutting, or wounding oaks during April through July leaves them vulnerable to oak wilt. / Photo Credit: Paul Cigan, Wisconsin DNR

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

With warmer spring weather fast approaching, the Wisconsin Department of Natural Resources (DNR) recommends protecting oaks from the often-fatal disease, oak wilt, by refraining from pruning, cutting or injuring oak trees from April through July.

Oak wilt is a serious disease that kills trees in the red oak group (including pin oak, northern red oak and black oak) and weakens those in the white oak group (bur oak, swamp white oak, white oak and English oak).

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Squirrels Can Damage Trees During Late Winter

Photo showing that squirrels have removed significant amounts of bark from a maple tree's trunk to get at the tasty cambium layer underneath.

Squirrels have removed significant amounts of bark from this maple to get at the tasty cambium layer underneath. / Photo Credit: Linda Williams, Wisconsin DNR

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

Squirrels can be fun to feed and fun to watch, but when they start damaging or killing your trees, well, that’s not so cute.

It’s the time of year when we start to have some warm days that allow sap to start moving in trees. If there are broken branches or damaged bark, the tree can drip sap. And that can attract squirrels.

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Squirrel Or Porcupine Damage: How Do You Know?

Photo showing squirrel tooth marks on a tree. Squirrel tooth marks are small and look like narrow scratches where the animals have removed the tree’s bark.

Squirrel tooth marks are small and look like narrow scratches where the animals have removed the tree’s bark. / Photo Credit: Linda Williams, Wisconsin DNR

By Linda Williams, Forest Health Specialist

Linda.Williams@wisconsin.gov or 920-360-0665

If something chewed the bark off your tree, how would you go about determining the culprit?

Quite a few animals can damage bark on trees, from deer and bears to rabbits and mice. But the damage from squirrels and porcupines can look very similar, especially from a distance. So, how can you tell the difference?

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Is That A Crack In My Tree?

By Olivia Witthun, DNR Urban Forestry Coordinator
Olivia.Witthun@wisconsin.gov or 414-750-8744

tree with frost crackWisconsin winters with subzero weather can create problems for our trees. Frost cracks are one of those problems we’re seeing an uptick of lately. These longitudinal openings can run the entire length of the trunk, often extend deep into the wood, and permanently damage a tree. In wintertime, the tree may even look like it’s splitting in half! Then warmer weather comes, and the crack seems to close, repeating this process annually. Over time, frost cracks may even develop a raised area where callus tissue develops in an attempt to close over the wound, only to reopen again next winter. Continue reading “Is That A Crack In My Tree?”

Post Your Forestry Jobs For Free

Have a job opening you need to get the word out about before the busy field season ramps up?

The UW-Stevens Point’s Wisconsin Forestry Center welcomes employers to send in their job openings using this email: wfc@uwsp.edu. Web links are preferred, but PDFs are also acceptable. Be sure to include job title, type of employment (full-time, part-time, temporary, internship, etc.), location and application due date. There is no cost for posting openings. Continue reading “Post Your Forestry Jobs For Free”

Run For The Trees

Now is the time to sign up for Run for the Trees: Happy Little (Virtual) 5K! Run, walk or roll to support tree planting and forest protection efforts in state parks. The program was started in 2019 when Bob Ross Inc. partnered with the Michigan Department of Natural Resources to raise awareness of and money for tree planting and has since expanded to 13 states. Continue reading “Run For The Trees”

A Wonderful Winter Display: Phomopsis Galls

Phomopsis galls are plentiful on branches of a 120-year-old red oak tree in Clark County, Wisconsin, in 2024.

Phomopsis galls are plentiful on branches of a 120-year-old red oak tree in Clark County, Wisconsin, in 2024. / Photo Credit: Kris Wimme, retired Wisconsin DNR forester

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

It is the perfect time of year to be on the lookout for galls – woody growths or swellings on tree branches that are typically oblong in shape and of varying sizes.

They can often be found on small branches, but occasionally they can affect large branches or even the main stem. Galls can occur for several reasons, ranging from fungi to bacteria to insect activity.

One type, Phomopsis gall, can be particularly impressive to see. Galls formed due to this native fungus mostly occur on oak, hickory and maple trees in Wisconsin.

 

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Frost’s Bite: How Do Insects Survive Winter?

An emerald ash borer larva overwinters by curling into a J shape inside a channel in an ash tree in Brookfield in 2019.

An emerald ash borer larva overwinters by curling into a J shape inside a channel in an ash tree in Brookfield in 2019. / Photo Credit: Bill McNee, Wisconsin DNR

By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg

Michael.Hillstrom@wisconsin.gov

As winter’s chill persists, Wisconsin Department of Natural Resources (DNR) Forest Health staff members are often asked how cold it needs to get to kill insects, especially invasives.

The answer varies from species to species, but many insects are well adapted to dealing with freezing winter temperatures. Some, such as monarchs, avoid the issue and migrate south for the winter. Others, such as multicolored Asian ladybeetles, annoy us with their presence in our homes and offices as they try to avoid the cold until spring.

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Spring Dreaming: Keep Invasive Plants Out Of Garden Plans

Originally planted as a garden ornamental, Japanese barberry can quickly escape cultivation and invade Wisconsin’s woodlands.

Originally planted as a garden ornamental, Japanese barberry can quickly escape cultivation and invade Wisconsin’s woodlands. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

Even though winter’s grip has taken hold in Wisconsin, many gardeners are already thinking ahead to the next spring planting season.

While dreaming of spring blooms and designing your next garden or landscape layout, be on the lookout for invasive plants that may try to weed their way into your plans.

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Now Is Time To Seek Out Spongy Moth Egg Masses

Large egg masses are seen on a tree at the Kettle Moraine State Forest-Southern Unit in 2021.

Large egg masses are seen on a tree at the Kettle Moraine State Forest-Southern Unit in 2021. / Photo Credit: Bill McNee, Wisconsin DNR

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

It might be a bit chilly these days, but spring is coming. When the weather warms up, the annual return of spongy moth caterpillars will begin.

There’s a way for landowners to make a dent in the population of the hungry caterpillars: Get out now to locate and properly dispose of spongy moth egg masses, produced by adult moths last summer.

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