Disease

Weather Whiplash Affects Pine Stands

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Swath of dead pine due to high water table mortality

A swath of pine dead due to high water table mortality in 2020 in northeast Wisconsin.

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

Many pine stands across central and northeast Wisconsin are being impacted by the change from high levels of precipitation to extreme drought that has occurred over the last 5-7 years.

Drastic or sudden changes can be particularly stressful to trees of all species, but especially to pine stands that prefer well-drained soil types.

Continue reading “Weather Whiplash Affects Pine Stands” →

What’s That Orange Goo?

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A slime mold perched on a vine.

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

What’s the orange goo on that tree?

Should I fight, or should I flee?

I bet forest health staff can ID!

Indeed, there are a number of types of orange goo in the woods during spring.

If it’s a lumpy mass of goo on a log, stump or mulch, then it’s probably a slime mold. Slime molds are an amoeba-like group of organisms called myxomycetes. They move very slowly to eat bacteria and organic matter. Slime molds are harmless, so unless it is covering something of value, just leave it be, and it will disappear on its own. Continue reading “What’s That Orange Goo?” →

Phomopsis Galls Found On Northern Red Oak

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By Linda Williams, DNR forest health specialist, Woodruff;
Linda.Williams@wisconsin.gov or 920-360-0665

Photo showing large Phomopsis galls on a tree before it has leafed out in the spring.

It is often easier to spot large Phomopsis galls before leaves come out in the spring.

Phomopsis galls are large woody swellings on the branches or main stem caused by a fungus. Across Wisconsin, Phomopsis galls can grow on hickory, especially bitternut hickory. However, in some areas of Wisconsin, they can occur on northern red oak.

Northern red oaks sometimes have hundreds of Phomopsis galls on the branches, ranging from as small as a tennis ball to as large as a basketball. Continue reading “Phomopsis Galls Found On Northern Red Oak” →

Slime Mold: Mysterious And Amazing

Posted on by akabelowsky

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

What can learn new things, move toward and acquire food, remember where food was and what foods are preferred, figure out the shortest route through a maze, remember where it has traveled and seem to disappear as quickly as it first appeared?

It’s slime mold, of course!

Continue reading “Slime Mold: Mysterious And Amazing” →

Sign Up For Oak Wilt Vector Emergence Emails

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By Kyoko Scanlon, Forest Pathologist, Fitchburg;
Kyoko.Scanlon@wisconsin.gov

With the recent warm-up and little snow on the ground in February, you may wonder if the insects responsible for transmitting oak wilt (oak wilt vectors) may emerge earlier this spring.

Though it is impossible to know precisely when they emerge, there is a tool that can be used to help you ease your anxiety a bit.

Continue reading “Sign Up For Oak Wilt Vector Emergence Emails” →

Green Light On For Oak Tree Work

Posted on by akabelowsky
Photo of fallen leaves from a red oak that show discoloration, an indication that the tree is infected with oak wilt.

Discolored fallen leaves from a red oak tree indicate that the tree is infected with oak wilt. / Photo Credit: Wisconsin DNR

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

With the weather taking its time to turn wintry, it’s a good time to remind landowners and work crews that now through the end of March is an ideal time to perform pruning, trimming and brush removal on and near oak trees.

This is a low-risk period for the trees to be infected with oak wilt, a fungal disease spread by beetles. When a red oak is infected with oak wilt, it will die that year. The disease also stresses white oaks, often proving fatal.

Continue reading “Green Light On For Oak Tree Work” →

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.

Continue reading “Oak Wilt Confirmed In Ashland County” →

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.

Continue reading “Don’t Let Tree Trouble Hitch A Ride On Firewood” →

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” →

Balsam Fir Mortality Similar To 2018 And 2020

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

Photo of balsam fir tree prematurely turning brown and red.

Scattered balsam fir trees in the Northwoods have suddenly turned brown and red this spring. / Photo Credit: Linda Williams, Wisconsin DNR

Scattered balsam fir trees in some areas of northern Wisconsin have suddenly turned rusty red to brown and are dying. These trees are not being impacted by spruce budworm and typically die with a full complement of needles.

The symptoms resemble what was observed in 2018 and 2020. So far, the number of trees being reported is smaller than what was seen in 2018 or 2020. Reports are still coming in, but they seem to be concentrated in northern areas of the state where we had extensive snowfall in late winter.

Continue reading “Balsam Fir Mortality Similar To 2018 And 2020” →