Forest Health News

Take Note: It’s National Firewood Month

A shed inside Mirror Lake State Park offers bundles of local firewood for sale. All staffed State Parks with campgrounds offer firewood for sale.

A shed inside Mirror Lake State Park offers bundles of local firewood for sale. All staffed State Parks with campgrounds offer firewood for sale. / Photo Credit: Wisconsin DNR

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

Are you generally hesitant to give hitchhikers a free ride?

October is National Firewood Awareness Month, and the Wisconsin Department of Natural Resources (DNR) urges state residents and visitors to follow the same line of thinking when it comes to moving firewood.

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Hillstrom Moves Into New Role With DNR

Photo of Mike Hillstrom, who became the Wisconsin Department of Natural Resources Invasive Forest Pest Coordinator on Sept. 9, 2024.

Mike Hillstrom became the Wisconsin Department of Natural Resources Invasive Forest Pest Coordinator on Sept. 9, 2024. He replaces Andrea Diss-Torrance, who retired on Jan. 24 after a 30-year career with the DNR. Hillstrom’s office will remain in Fitchburg, where this photo was taken. / Photo Credit: Art Kabelowsky, Wisconsin DNR

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

So, what’s bugging Mike Hillstrom these days?

That question has taken on new importance for forestry professionals, now that Hillstrom has stepped into an expanded role with the Wisconsin Department of Natural Resources (DNR)’s Forest Health team. Hillstrom started Sept. 9 as the DNR’s invasive forest pest coordinator.

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Fall Means Hunting — For Spongy Moth Egg Masses

Photo of spongy moth egg masses on a tree.

Each egg mass laid by a spongy moth carries 300 or more eggs. Caterpillars will emerge in spring. Egg masses can be removed with care during fall and winter months to prevent the emergence of caterpillars. Photo Credit: / Wisconsin DNR

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

The Wisconsin Department of Natural Resources (DNR) is encouraging property owners to seek out and dispose of spongy moth egg masses, which were produced by adult moths during the summer.

Each spongy moth egg mass contains hundreds of eggs that will hatch into hungry, leaf-eating caterpillars in the coming spring. Large numbers of these invasive caterpillars can be a tremendous nuisance that may cause tree mortality.

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Time Is Right For Oak Tree Work

Photo of a roadxside flail mower that can make work easier and more productive for town crews, but can cause deadly damage to oak trees in the vicinity.

Flail mowers can make work easier and more productive for town crews, but the Wisconsin Department of Natural Resources urges workers and managers to save any work that could damage oak trees for fall and winter, when the risk of the fungal disease oak wilt is minimal. / Photo Credit: Wisconsin DNR

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

Do you know of a state, county, municipal or private crew that has been itching to do some work involving oak trees? Or are you a landowner itching to do some oak pruning or cutting?

Well, the time has arrived for smart and safe work on oaks.

It’s important for crews and managers to know that any damage done to oak trees from April 1 through at least mid-July — many say into September — could lead to a quick death for that tree. Frequently, one tree’s infection will also lead to eventual mortality for neighboring oaks.

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Aspen Leaves Dropping Early

Early leaf disease causes aspen trees in Northeast Wisconsin to look thin, with small, off-color leaves.

Early leaf disease causes aspen trees in Northeast Wisconsin to look thin, with small, off-color leaves. / Photo Credit: Linda Williams, Wisconsin DNR

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

Did you notice the many aspen trees in the Northwoods starting to drop their leaves in early September? These leaves were yellow with brown blotches or were brown and curled, and there were a lot of them falling.

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Cottony Ash Psyllid Challenging Black Ash

Closeup photo of an adult cottony ash psyllid on a leaf.

Adult psyllids are quite small and can blend in with their surroundings. / Photo Credit: Linda Williams, Wisconsin DNR

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

Have you noticed black ash trees that have tightly curled leaves in scattered clumps, with lots of bare areas on the branches?

The problem might be cottony ash psyllid (Psyllopsis discrepans), a tiny, sap-sucking insect that has been in North America for almost 100 years but was first identified in Wisconsin in 2006. Its presence was reconfirmed in 2023, when it was found in several additional counties around the state. Since then, it has been identified in even more counties.

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Don’t Be Blinded By Invasives While Hunting

Photo of a turkey hunter in a blind.

Whether hunting for turkey, deer or other prey, don’t use invasive plants as a natural hunting blind. / Photo Credit: Wisconsin DNR

By Erika Segerson-Mueller, DNR Invasive Plant Program Specialist, Oshkosh Service Center;
Erika.SegersonMueller@wisconsin.gov or 715-492-0391

As fall settles in and hunting seasons start to open across the state, many Wisconsinites’ thoughts have turned to tree stands, blinds and all things hunting.

Planning out your perfect capture means giving yourself the best chance possible, whether slipping into or out of your tree stand or ground blind. One popular idea is camouflaging your path – using plants or trees as a natural blind so you can reach your spot without being seen by deer or other animals.

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Galls On Oak Leaves Are Plentiful, Varied

Closeup photo of Callirhytis piperoides, a gall that seems to erupt from an oak leaf's midrib and can be on top or bottom of the leaf.

Callirhytis piperoides is a gall that seems to erupt from an oak leaf’s midrib and can be on top or bottom of the leaf. It is found on the leaves of young northern red oak. Galls will fall off the leaf so that the insect can complete its development within the gall on the ground. / Photo Credit: Linda Williams, Wisconsin DNR

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

Have you noticed any galls on oak leaves or twigs? Don’t be too surprised. There are many different types of galls that form on oaks – some are smooth, some are spiky and others are fuzzy.

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Fall Webworm Spins Up Attention

Photo of a web spun by fall webworms seen on a tree branch in Oshkosh in September 2024.

Fall webworm is seen on a tree branch in Oshlkosh on Sept. 9, 2024. / Photo Credit: Bill McNee, Wisconsin DNR

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

The native insect known as fall webworm (Hyphantria cunea) is back in the news.

The caterpillars don’t draw much attention on their own; instead, what catches the eye at this time of year are the large webs (or “tents”) that they create on the tips of tree branches.

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Pine False Webworm Makes Appearance

A closeup photo shows that pine false webworm eggs look like a string of sausages, displayed here on a white pine needle.

A closeup photo shows that pine false webworm eggs look like a string of sausages, displayed here on a white pine needle. / Photo Credit: Liunda Williams, Wisconsin DNR

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

Pine false webworm (Acantholyda erythrocephala) is not a very common insect in Wisconsin, but damage from larval feeding can occasionally be seen. The insects prefer to feed on white pine in Wisconsin, although reference material says they will also feed on red pine, jack pine and scotch pine.

Damage was reported as minor in the central part of the state from 1953 to 1961. In 1995, 1997, 2002, 2004 and 2006, it was once again observed as a minor pest feeding on red or white pine in the central part of the state, particularly Portage, Waupaca and Waushara counties. In 2024, a few scattered young white pine trees in Oneida and Vilas counties were observed with significant defoliation.

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