By Michael Hillstrom, Forest Health Specialist, Fitchburg; Michael.Hillstrom@wisconsin.gov
Caterpillars wandering the snow in February? Yes, the “winter cutworm,” Noctua pronuba, is a hardy species that is sometimes observed active in temperatures as low as the 20s.
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”
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.
By Linda Williams, DNR Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov or 920-360-0665
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”
By Bill McNee; DNR Forest Health specialist, Oshkosh;
Bill.McNee@wisconsin.gov or 920-360-0942
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”
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”
Paul Cigan, DNR Forest Health Specialist, Hayward;
Paul.Cigan@wisconsin.gov or 715-416-4920
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.
By Linda Williams, DNR Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov or 920-360-0665
Bronze birch borer has attacked these trees, and parts of the tree above the attack site are thin and declining. / Photo Credit: Linda Williams, Wisconsin DNR
Bronze birch borer (Agrilus anxius) is a native beetle that attacks birch trees. As adults emerge from the bark, they create small, D-shaped exit holes, similar to emerald ash borer but smaller.
Bronze birch borer attacks stressed trees, and the source of the stress can be anything from drought, flooding, defoliation or old age.
Continue reading “Bronze Birch Borer Attacks Stressed Birch”
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.
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.
