Forest Health News

First Recovery of Emerald Ash Borer Enemy Made

Posted on by akabelowsky

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

Map showing Spathius Galinae recovery in Manitowoc County

Sites where EAB biological controls have been recovered as of March 2023. The Spathius galinae recovery site is indicated by a red star. Blue dots show Tetrastichus planipennisi recovery sites. Municipal EAB detections are in green. Map: Wisconsin DNR

Two adult wasps, collected last December as pupae from an emerald ash borer (EAB) gallery at Kiel Marsh State Wildlife Area in Manitowoc County, have recently been identified as Spathius galinae.

This find marks the first time that S. galinae has been recovered in Wisconsin, confirming that the adult wasps released at this site over the last few years were able to attack EAB larvae and reproduce successfully. The “EAB wasps” were released as biological controls to help reduce EAB populations over the long term.

This wasp species has a longer ovipositor than the other EAB larval parasitoid currently released in Wisconsin (Tetrastichus planipennisi), allowing S. galinae to attack EAB larvae that are beneath thicker bark.

Spathius galinae was first released in Wisconsin in 2016, and approximately 1,000 of this species were released at Kiel Marsh in 2019 and 2020. Recovery surveys are conducted several years after initial releases, giving the wasps time to reproduce and spread. Continue reading “First Recovery of Emerald Ash Borer Enemy Made” →

Aerial Spraying Set For Four State Sites

Posted on by akabelowsky

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

Spray aircraft used in spongy moth control

Spray aircraft used in spongy moth control. Photo: Bill McNee

At a suitable time between early May and early June, an airplane will spray parts of four DNR properties to reduce the population of spongy moth caterpillars (formerly known as gypsy moth). Treatment dates will depend on weather conditions and caterpillar development.

This year’s high populations threaten to strip trees of their leaves and possibly kill high-value trees at these properties.

Continue reading “Aerial Spraying Set For Four State Sites” →

Heterobasidion Root Disease Approaches

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By Alex Feltmeyer, Forest Health Specialist, Plover, Alexandra.Feltmeyer@wisconsin.gov or 715-340-3810

A Heterobasidian root disease fruiting body at the base of a white pine sapling

A Heterobasidion root disease fruiting body is found at the base of a white pine sapling in the understory. Photo: Wisconsin DNR Forest Health

Heterobasidion Root Disease (formerly annosum root rot or Fomes root rot) is a serious disease of conifers that causes reduced height, shoot and diameter growth along with thin and yellowish/red foliage, ultimately causing mortality.

The disease becomes established in a new stand when spores of the fungus land on freshly cut stumps made by any forest management that creates cut stumps. After the disease becomes established, it spreads underground through root systems into adjacent trees. In this way, we often find pockets or groups of trees in various stages of decline.

Movement through the root systems contributes to significant spread throughout stands of conifers, impacting the regeneration of conifers within these pockets.

Mortality usually starts occurring three to eight years after a thinning operation. During this time, perennial fruiting bodies of the fungus begin to develop around the base of cut stumps or dead trees.

Continue reading “Heterobasidion Root Disease Approaches” →

Hungry Squirrels Find Trees Tasty

Posted on by akabelowsky

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

Maple branches with light colored areas where squirrels removed bark.

Squirrels remove the bark of maples, leaving bright bare spots. Photo: Wisconsin DNR

It’s the time of year when we start to see scattered maple trees stripped of their bark. Squirrels cause this damage — which can be limited to a few small areas the size of a tennis ball or can extend to cover many feet of branches or the main stem.

The squirrels are going after the cambium layer, just under the bark, that tastes slightly sweet from the sap. Smooth bark is easier for squirrels to chew, so young trees or branches with thin bark are likelier to be stripped than those with older, furrowed bark.

At this time of year, the pale wood of the branches that have had the bark stripped off is nearly white; later in the season, this wood will darken or even turn black with sooty mold. This type of feeding can remove enough bark to girdle the branches or the main stem, causing the tree to die from that point to the end of the branch.

Branches that are not completely girdled will continue to grow, and callus tissue will begin to grow over the wounds. If branches are nearly girdled, they may leaf out this spring and then suddenly wilt and die as hot weather hits because the tree can’t deliver enough water to keep those leaves alive. Continue reading “Hungry Squirrels Find Trees Tasty” →

Lab Assistant Departs

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

Another photo will be hung on the unofficial “Wall of Fame” bulletin board inside the Department of Natural Resources Forest Health Lab in Fitchburg.

Ethan Wachendorf, who joined DNR as a laboratory assistant on May 23, 2022, departed on Thursday, March 23, to pursue a Master of Science in plant pathology at Michigan State University in East Lansing.

Outgoing Forest Health lab assistant Ethan Wachendorf at a microscope

Ethan Wachendorf

Wachendorf started as a summer lab assistant, but at the start of 2023 became a dual LTE, working as the lab assistant. The Colorado native joined the DNR after earning a bachelor’s degree in government (with a minor in biology) from Lawrence University in Appleton.

Wachendorf said he was drawn to Michigan State for post-graduate studies after working with Dr. Monique Sakalidis, who runs the university’s forest pathology lab.

“I’ll be working on oak wilt testing and management techniques, such as herbicide, fungicide, rapid response and the way the trees change physiologically,” Wachendorf said.

He will work full-time at the Michigan State lab until the fall semester, when he will split his time between lab duties and classwork.
His Wisconsin impressions include how “Midwest nice” the people are, how good the beer is, and how cold it gets — and stays — in the Badger state.

First Anniversary Of Spongy Moth’s Name Change

Posted on by patricialindquist
Spongy moth caterpillar

Spongy moth caterpillar. Photo credit: Jon Yuschock, Bugwood.org

March 2, 2023, marks one year since a new common name for Lymantria dispar, spongy moth, replaced the prior name of this insect, “gypsy moth.” This change was necessary because the word “gypsy” is an ethnic slur for the Romani people and the former common name equated people with insects. This is the first name change undertaken by ESA (Entomological Society of America)’s Better Common Names Project.

The current name—derived from the common name used in France and French-speaking Canada, “spongieuse“—refers to the moth’s sponge-like egg masses. Lymantria dispar is a damaging pest. This current name is a critical move in public awareness that focuses on an important feature of the moth’s biology while moving away from an outdated term. We encourage you to review any materials you may have on your website, ordinances and other material related to forest pests to ensure they are in accordance with this name change.

Continue reading “First Anniversary Of Spongy Moth’s Name Change” →

Wisconsin DNR 2022 Forest Health Annual Report

Posted on by patricialindquist

By Becky Gray, Forest Health Team Leader, Rebecca.Gray@wisconsin.gov

The Wisconsin Department of Natural Resources’ Forest Health team recently completed the 2022 Forest Health Annual Report. The report summarizes impacts from pests, diseases and weather on the health of Wisconsin’s forests. Highlights from 2022 include:

  • Spongy moth’s rising numbers and evaluation of control techniques;
  • emerald ash borer continuing to spread and kill ash trees;
  • possible new biological control of buckthorn; and
  • drought and flooding impacts alongside insect infestations.

Read the report here.

2022 Forest Health Annual Report

Sign Up For Oak Wilt Vector Emergence Estimate Daily Email Notification

Posted on by patricialindquist

By Kyoko Scanlon, Forest Pathologist, Fitchburg, Kyoko.Scanlon@wisconsin.gov or 608-235-7532

Oak wilt is a serious disease that occurs when insects carrying oak wilt fungal spores land on a healthy oak tree’s fresh wound. To prevent oak wilt infections, it is important to avoid pruning, wounding and harvesting oaks when these insects are abundant, generally from April through July. Predicting exactly when these insects start to emerge in the spring can be difficult as their emergence is highly weather-dependent, and spring weather varies significantly from year to year.

In 2021, the Oak Wilt Vectors Emergence Thermal Model tool, a unique estimation tool, was developed as a collaborative project between the University of Wisconsin-Madison and the Wisconsin DNR to help with these predictions. This online tool offers localized recommendations about the emergence status of the two most important insects that transmit oak wilt in Wisconsin. The interface uses a degree-day model (Jagemann et al., 2018) constructed from insect trapping data and actual weather data, which helps refine the beginning of the periods when you should avoid pruning, wounding or harvesting oaks.

A screen shot of the oak wilt vector emergence homepage where the location and date data is entered to model growing degree days.

UW Extension’s Oak Wilt Vectors Emergence Thermal Model can help predict when oak wilt vectors may be coming. Photo Credit: UW Extension

Continue reading “Sign Up For Oak Wilt Vector Emergence Estimate Daily Email Notification” →

Make Plans To Control Spongy Moth Before The Eggs Hatch

Posted on by patricialindquist

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

Spongy moth (formerly known as gypsy moth) egg masses typically begin to hatch in April as temperatures warm. Each mass that hatches may produce up to 1,000 leaf-eating caterpillars.

Now is a great time to inspect your trees for egg masses and treat or remove any masses within reach. Wisconsin weather has been favorable for this pest over the last three years and populations have grown.

Photo of three spongy moth egg masses on the underside of a pine branch in Walworth County.

Three spongy moth egg masses on the underside of a pine branch in Walworth County. Photo: Bill McNee, Wisconsin DNR.

Continue reading “Make Plans To Control Spongy Moth Before The Eggs Hatch” →

Spongy Moth Management Webinar: March 8 at 6 p.m.

Posted on by patricialindquist

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

Spongy moth populations increased dramatically in 2022 and the outbreak is expected to continue in 2023.

Landowners interested in learning more about spongy moth management options are encouraged to attend an upcoming webinar hosted by UW Extension at 6 p.m. on March 8, 2023.

This is a free event, but registration is required. DNR Forest Health Specialist Mike Hillstrom and UW-Madison Insect Diagnostic Lab entomologist PJ Liesch will discuss a variety of effective management tactics for reducing spongy moth damage in varied settings from high value urban trees to forests.

A flyer for an upcoming webinar about spongy moth management that will take place virtually at 6pm on March 8, 2023.

UW Extension’s spongy moth management webinar can help you prepare to care for your land this spring.