Northern WI Forest Health

Watch For Spongy Moth Caterpillar Diseases

By Bill McNee, DNR Forest Health Specialist, Oshkosh or 920-360-0942

With this spring’s weather bringing above-average rainfall across most of Wisconsin, we will likely see moderate to heavy mortality of spongy moth caterpillars at many locations this summer.

Last year, the statewide May-June period was the third-driest since recordkeeping began in the late 1800s, according to the NOAA National Centers for Environmental Information. As a result, the effectiveness of the caterpillar-killing fungus, Entomophaga maimaiga, was limited. Spring 2024 is noticeably wetter, and thus, increased effectiveness of E. maimaiga is likely.

Continue reading “Watch For Spongy Moth Caterpillar Diseases”

What’s That Orange Goo?

A slime mold perched on a vine.

By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg;

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?”

Emerald Ash Borer Detected In Washburn, Taylor Counties

By Paul Cigan, DNR forest health specialist, Hayward; or 715-634-9232

Photo of an emerald ash borer on a tree

The emerald ash borer was detected in the Wisconsin counties of Taylor and Washburn in April, making them No. 70 and No. 71 of Wisconsin’s 72 counties that have confirmed presence of the invasive insect.

The emerald ash borer (EAB) has been detected for the first time in Washburn and Taylor counties, making them the No. 70 and No. 71 of Wisconsin’s 72 counties to have a confirmed detection of the invasive insect.

Here are the details of the most recent discoveries: Continue reading “Emerald Ash Borer Detected In Washburn, Taylor Counties”

Phomopsis Galls Found On Northern Red Oak

By Linda Williams, DNR forest health specialist, Woodruff; 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”

Watch For Hemlock Woolly Adelgid

By Linda Williams, Forest Health Specialist, Woodruff;, 920-360-0665

Landowners with hemlock and anyone who walks through or works in hemlock stands can help watch for signs of hemlock woolly adelgid (HWA).

This invasive insect has not yet been identified in Wisconsin, but it has been found in seven counties in Michigan’s Lower Peninsula. The insect sucks the sap of hemlock trees, and large populations can cause the decline and mortality of hemlock over 4 to 10 years, depending on the health of the tree and population levels of HWA. It’s vital to find infestations as early as possible to allow multiple options for control and management.

Continue reading “Watch For Hemlock Woolly Adelgid”

Slime Mold: Mysterious And Amazing

By Linda Williams, Forest Health Specialist, Woodruff;, 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”

Emerald Ash Borer Spreads Through The North

By Paul Cigan, DNR Forest Health Specialist, Hayward;, 715-416-4920

This winter, the spread and impact of emerald ash borer (EAB) have been confirmed in several new northern townships in previously invaded counties.

These include Marengo (Ashland County); Gordon, Hawthorne and Oakland (Douglas County); Cadott and Colburn (Chippewa County) and Balsam Lake and St. Croix Falls (in Polk County).

Continue reading “Emerald Ash Borer Spreads Through The North”

Feeding Aphids Cause Spruce To Wilt

By Linda Williams, Forest Health Specialist, Woodruff;, 920-360-0665

Have you ever wondered just how much sap can be sucked out of a tree by aphids?

Aphids insert their piercing, sucking mouthparts into needles, twigs or bark, depending on the species of aphid.

Once their mouthparts are inserted, they begin to suck sap and will excrete excess moisture as small droplets of water called honeydew.

Continue reading “Feeding Aphids Cause Spruce To Wilt”

Squirrel Damage To Maple Trees Showing Up Earlier This Winter

By Linda Williams, DNR Forest Health Specialist, Woodruff; or 920-360-0665

Photo of a maple tree with some bark removed by squirrel feeding.

Squirrels have stripped off the bark of this maple tree to get at the sweet cambium layer under the bark. / Photo Credit: Linda Williams, Wisconsin DNR

Typically in the spring, squirrels can cause damage to maple trees by removing bark from branches and the main stem after the trees have been frozen all winter and the weather starts to warm up. This fall, before the January cold spell, temperatures had warmed up by mid-November and remained warm throughout December.

As a result, starting in late November fresh squirrel damage was being noted on some scattered maples in north central Wisconsin. Damage progressed throughout December and some trees have more than half of the bark removed from branches and the main stem. The sight of scattered bits of bark around the base of these trees is another sign of squirrel activity.

Continue reading “Squirrel Damage To Maple Trees Showing Up Earlier This Winter”