Northern WI Forest Health

Phomopsis Galls Found On Northern Red Oak

Posted on by akabelowsky

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” →

Watch For Hemlock Woolly Adelgid

Posted on by akabelowsky

By Linda Williams, Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov, 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

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” →

Emerald Ash Borer Spreads Through The North

Posted on by akabelowsky

By Paul Cigan, DNR Forest Health Specialist, Hayward;
https://dnr.wisconsin.gov/topic/foresthealth/staff, 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

Posted on by akabelowsky

By Linda Williams, Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov, 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

Posted on by akabelowsky

By Linda Williams, DNR Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov 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” →

Woodpecker Damage On Ash Trees May Indicate Emerald Ash Borer

Posted on by akabelowsky

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

Photo showing woodpecker damage on an ash tree trunk, an early sign the tree might be infested with emerald ash borer.

Woodpecker damage is an early sign an ash tree might be infested with emerald ash borer. / Photo Credit: Wisconsin DNR

The Wisconsin Department of Natural Resources (DNR) encourages property owners to watch for woodpecker damage to their ash trees this winter. If damage is found, property owners should make plans to take action in the spring.

Woodpecker damage, often called “flecking,” happens when birds peck away some of a tree’s bark to access the larvae underneath. Flecking is a common early sign that an ash tree might be infested with emerald ash borer (EAB), an invasive insect. EAB is the most damaging threat to Wisconsin trees, killing more than 99% of the untreated ash trees it infests.

Continue reading “Woodpecker Damage On Ash Trees May Indicate Emerald Ash Borer” →

Leafminer Creates Green Bay Packers Colors On Aspen Leaves

Posted on by akabelowsky
Photo of an aspen leaf that fell in the fall showing a “green island” due to leafminer feeding.

An aspen leaf that fell in the fall showing a “green island” due to leafminer feeding. / Photo Credit: Linda Williams, Wisconsin DNR

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

Most aspen leaves that fell this fall were a beautiful yellow gold color, but every so often some could be found that were yellow with a green strip on them. Were the aspen trees supporting the Green Bay Packers? No. The green stripe was an indication of the presence of a tiny leafmining caterpillar.

Leafminers are tiny caterpillars that live and feed within a leaf. These tiny caterpillars may produce blotch mines or serpentine mines that create lines on the leaf.

Continue reading “Leafminer Creates Green Bay Packers Colors On Aspen Leaves” →

Forest Health Forecast For 2024

Posted on by akabelowsky

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

An aerial photo of oak and aspen forests showing heavy defoliation from spongy moth.

Oak and aspen forests with heavy defoliation from spongy moth. Additional defoliation coupled with ongoing drought in the upcoming 2024 growing season is expected to put significant stress on affected forests. / Photo Credit: Paul Cigan, Wisconsin DNR

Maintaining a healthy and productive forest often requires — more than ever before — a working knowledge of how to anticipate, prevent and mitigate environmental stressors that threaten to undermine it. The list of stressors includes drought, impact of forest insects and diseases.

In a recent and timely article, Denise Thornton of My Wisconsin Woods taps the expansive knowledge of the DNR’s Forest Health team and a state climatologist to bring focus to the threats facing forests this year.

She also lists steps that can be taken to ensure health and proactivity are maintained in your forests.