Forest Health News

Please Report Beech Scale Outside Of Door County

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Map showing locations of known moderate or high beech scale populations as of November 2023, in red.

Locations of known moderate or high beech scale populations as of November 2023 are shown in red. High populations are known to be widespread in Door County. / Map Credit: Bill McNee, Wisconsin DNR

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

Earlier this year, we reported that high populations of the non-native insect beech scale (Cryptococcus fagisuga) were identified for the first time in Marinette and Sheboygan counties. Since then, several more sites with moderate or high scale populations have been identified (see map).

Continue reading “Please Report Beech Scale Outside Of Door County” →

Make Your 2024 Spongy Moth Treatment Plans Early

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Photo of a finger pointing to a tan-colored spongy moth egg mass on a tree.

A finger points to a tan-colored spongy moth egg mass on a tree. / Photo Credit: Bill McNee, Wisconsin DNR

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

If the 2024 spring and summer weather conditions are favorable for the spongy moth (Lymantria dispar) population, the current outbreak will continue and spread to other parts of Wisconsin. Property owners are encouraged to examine susceptible host trees (including oak, birch, crabapple, aspen and willow) and make plans to manage them.

In summer 2023, Wisconsin saw a record amount of defoliation. State agencies received many calls from property owners urgently seeking a tree care business to control a large caterpillar infestation.

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Keep Invasive Plants Out Of Spring Garden Plans

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Photo of the invasive plant Japanese barberry

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

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

While winter is just beginning to creep in on 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, consider invasive plants that may try to weed their way into your plans.

Many invasive plants that are problematic for Wisconsin forests started as garden ornamentals. Although Wisconsin regulates 145 plants under the invasive species rule NR 40 prohibiting their sale, it’s essential to check your selections before purchasing and choose native plants when possible.

Continue reading “Keep Invasive Plants Out Of Spring Garden Plans” →

Harvest Timing Affected By Spongy Moth

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Photo showing numerous spongy moth egg masses on an oak tree in Walworth County, Wisconsin

Numerous spongy moth egg masses on an oak tree in Walworth County. / Photo Credit: Bill McNee, Wisconsin DNR

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

Forest managers planning silvicultural treatments in stands susceptible to spongy moth (Lymantria dispar) – such as those containing many host species, including oak, birch, aspen and basswood – are encouraged to conduct annual egg mass surveys before treatment.

Surveys make it possible to predict if heavy defoliation is likely. If more than 30 egg masses are found in a sample area – a circle with a 37-foot diameter – then heavy defoliation is expected in the spring, and management activities should be altered or delayed until an outbreak has ended. Continue reading “Harvest Timing Affected By Spongy Moth” →

Video Reminds Public Of Impact Of Heterobasidion Root Disease

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Photo frame from a DNR-produced video on heterobasidion root disease

A Wisconsin Department of Natural Resources video on Heterobasidion root disease shows ways to identify the disease and presents best management practices. / Photo Credit: Wisconsin DNR

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

Now is an excellent time to look for symptoms of Heterobasidion root disease (HRD), a fungal disease that attacks and kills pine and spruce trees. The disease is present in 30 of Wisconsin’s 72 counties.

The Wisconsin Department of Natural Resources has produced a video, a fact sheet and a booklet of silvicultural guidelines to manage the disease. The video and other links are on the DNR’s Forest Health webpage for HRD.

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Oak Wilt Confirmed In Ashland County

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Map showing Wisconsin counties in which oak wilt has been detected.

With the addition of Ashland County, oak wilt has now been detected in 66 of Wisconsin’s 72 counties. / Map Credit: Wisconsin DNR.

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

Oak wilt, a deadly disease of oaks, has been found for the first time in Ashland County.

The Wisconsin Department of Natural Resources (DNR) confirmed the find in wood samples from a red oak tree in the town of Gordon.

“There is always risk of oak wilt spread into new and relatively uninfested areas in northern Wisconsin, such as Ashland County, so it’s always best to practice oak wilt prevention wherever possible to significantly reduce that risk,” said Paul Cigan, a DNR forest health specialist based in Hayward.

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Avoid Ash Trees When Placing Deer Stands

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Photo of hunter climbing into tree-mounted deer stand.

It is important to place and maintain tree stands carefully as you prepare for the upcoming deer hunting season. / Photo Credit: Wisconsin DNR

By Bill McNee, Forest Health Specialist, Wisconsin DNR;
Bill.McNee@wisconsin.gov; (920) 360-0942

The Wisconsin Department of Natural Resources (DNR) cautions hunters to avoid placing deer stands in or near ash trees this deer hunting season.

Most ash trees in the southern half of Wisconsin, Door County and the Mississippi River counties are dead or dying from emerald ash borer infestation. Although emerald ash borer is not as widespread in other parts of the state, the invasive insect continues to be found at additional locations throughout the state and unreported infestations also are likely.

Continue reading “Avoid Ash Trees When Placing Deer Stands” →

Don’t Let Tree Trouble Hitch A Ride On Firewood

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Photo of spongy moth egg masses attached to a piece of firewood

A pair of spongy moth egg masses attached to a piece of firewood. Moving this firewood to another site could put trees at that site at risk in the spring. / Photo Credit: Wisconsin DNR

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

Are you generally hesitant to give hitchhikers a free ride?

October was National Firewood Awareness Month, and even though November has arrived, the Wisconsin Department of Natural Resources (DNR) continues to urge residents and visitors to follow the same line of thinking when it comes to moving firewood.

That’s because tree-killing hitchhikers often lurk on or in firewood — including spongy moth, emerald ash borer, the fungus that causes oak wilt and other invasive insects and fungi. When untreated, infested firewood is transported away from where the tree died, those pests and fungi can later emerge to attack trees at the new site. This can happen whether that new location is in the next town or hundreds of miles away.

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Oak Mortality Increases In 2023

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Photo of a bur oak tree more than 100 years old showing canopy dieback and epicormic branching due to twolined chestnut borer

A bur oak more than 100 years old exhibits canopy dieback and epicormic branching caused by twolined chestnut borer. / Photo Credit: Wisconsin DNR

By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg
Michael.Hillstrom@wisconsin.gov

White, red and bur oaks have been experiencing increased mortality in Wisconsin and neighboring states over the last few years.

The causes of mortality are varied, but two-lined chestnut borer (TLCB) is the most common culprit. Wisconsin has switched from a period of historically wet years (2017-2020) to drought conditions that have become more severe each year (2021-2023). Add in frost damage, storm damage, increased growing season length and aging forests and the environmental recipe exists for stressed oaks that are more susceptible to attack by insects and diseases.

Continue reading “Oak Mortality Increases In 2023” →

Watch For Rare Fall Garlic Mustard Blooms

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Photo of unusual garlic mustard plant flowering in the fall

Have you seen an unusual case of garlic mustard flowering twice in the same season? If so, please send a report to invasive.species@wisconsin.gov. / Photo Credit: Frederick Hengst, Wisconsin DNR

By Mary Bartkowiak, DNR Invasive Plant Program Coordinator, Rhinelander
Mary.Bartkowiak@wisconsin.gov or 715-493-0920

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

Typically a biennial plant, garlic mustard blooms in the spring. So, it sounds crazy to find the plant blooming again in October.

Although garlic mustard might be taking advantage of an extended growing season, this second bloom also may be cause for concern — or, at least, careful monitoring.

Wisconsin Department of Natural Resources Tax Law Forestry Specialist Frederick Hengst discovered this “mutant” specimen in early October while on a landowner visit near Wild Rose. The plant appears to have flowered and set seed several months earlier, but then re-flowered on the same stem.

Continue reading “Watch For Rare Fall Garlic Mustard Blooms” →