EAB Identified In Lincoln County For The First Time, Continues Spread Into Northern Wisconsin

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

Emerald ash borer (EAB) continues to spread into areas of Northern Wisconsin and was detected for the first time in Lincoln County, in the Town of Harrison and the City of Tomahawk. EAB was first identified in Wisconsin in 2008, only 14 years ago. It is now in 62 of Wisconsin’s 72 counties.

S-shaped markings in an ash tree trunk where a hatchet has removed the bark.

S-shaped galleries under the bark of this ash were created by EAB larvae. You can also see epicormic branches (water sprouts) coming out of the trunk. These are a sign of significant stress in the tree. Photo Credit: Wisconsin DNR

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90 New Municipal Detections Of Emerald Ash Borer In 2021

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

In 2021, emerald ash borer was found in 90 more communities in Wisconsin than in 2020, including 10 cities, 14 villages and 66 towns. This increased the total number of communities with a reported emerald ash borer detection 11% to 898 at the end of 2021.

Emerald ash borer was confirmed for the first time in Barron, Iron and Langlade counties during the year. It has now been found in 61 of Wisconsin’s 72 counties and confirmed on Oneida Nation land, and we believe additional unreported infestations are present.

Municipal emerald ash borer detections during 2021 are shown in orange. Older detections are shown in green or blue. Map courtesy of Wisconsin Department Agriculture, Trade and Consumer Protection.

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Upcoming Webinars: EAB University And TREE Fund

The EAB University Spring 2022 Webinars are right around the corner. All webinars are free, and many count towards continuing education programs.

Can’t watch them live? No problem! All webinars are recorded and posted afterward.

Check out the EAB University Spring 2022 webinars and register for them here. All sessions begin at 10 a.m. CST.

  • Feb. 24: The Biology and Management of the Invasive Spotted Lanternfly. Holly Shugart, Ph.D. Postdoctoral Scholar, Pennsylvania State University
  • March 1: Firewood Rules, Certifications, and Recommendations across the USA.
    Leigh Greenwood, Forest Health Program Director, North America Region, The Nature Conservancy 
  • March 3: The Worst Kind of Snowbird: The Invasion of Asian Longhorned Beetle in South Carolina. David Coyle, Assistant Professor and State Extension Specialist, Clemson University 

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Climate Impacts On Forest Insects

Climate change may impact forest insects in a variety of ways that will likely put stress on the forest. Warmer temperatures, altered precipitation patterns, more frequent extreme weather events and longer growing seasons are a few consequences of climate change that may shape the effects of insects in future forests. A changing climate may impact insects as:

  • Warmer temperatures accelerate larval development and increase insect populations.
  • Extended growing seasons allow for more generations of insects each year.
  • Altered leaf chemistry modifies insect host plant preferences.
  • Extreme weather events damage and stress forests, resulting in attacks by native and non-native insects.
  • Warmer temperatures allow insects to expand their range and occupy new areas.

Many examples of insects responding to climate change have already been documented. Two examples are:

1) Mountain pine beetle expanding its geographic range in the western U.S. and infesting a new host tree species during the most recent outbreak; and

2) Eastern larch beetle having an additional generation each year that has resulted in an unprecedented 20-year outbreak in Minnesota. Continue reading “Climate Impacts On Forest Insects”

Forest Health In The Statewide Forest Action Plan

The forest health chapter of Wisconsin’s 2020-2030 Statewide Forest Action Plan, completed in June 2020, highlights the impacts of insects, diseases, invasive plants and worms in Wisconsin’s forests.

Forest health experts from government agencies, universities and tribes worked together to evaluate these current impacts. They then developed goals and strategies to help the forestry community refine how it will invest state, federal and partner resources to address major forest health management and landscape priorities over the next ten years.

Forest health is a critical component of the plan because native and non-native pests increase tree mortality to a level that negatively affects forest stocking levels, clean water, wildlife habitat and raw material for wood products. This causes economic losses and undesirable management outcomes. Continue reading “Forest Health In The Statewide Forest Action Plan”

Planting and Seeding Trials In The Wake Of Ash Decline

Swamp White Oak seedling planted in a black ash replacement trial. Credit: Wisconsin DNR

The emerald ash borer (EAB) is causing widespread mortality of both upland and lowland ash. Black ash (and to a lesser extent green ash) is a forest wetland species that helps prevent sites from swamping through evapotranspiration. With the loss of ash in these systems, forest practitioners are developing silvicultural strategies to minimize the impacts through planting and seeding trials.

Acorn Weevils Make Acorns Float

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

Have you seen small round holes in acorns? These holes are a sign of acorn weevil damage that can occur in all Wisconsin oak species.

In a pile of brown and tan acorns, two have small round pencil-tip sized holes caused by acorn weevil larvae burrowing out from the inside.

Two acorns show exit holes of acorn weevils. / Photo Credit: Wisconsin DNR

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Take Action! Look For Gypsy Moth Egg Masses

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

In 2021, gypsy moth populations increased for a second consecutive summer due to favorable weather conditions. Populations typically increase with an average or mild winter, below average spring precipitation and above average May through June temperatures.

Regional variation in weather can result in significant differences in populations. If weather conditions are favorable again in 2022, the most noticeable increase in caterpillar numbers would likely occur in southern counties, where conditions were driest during this past spring and summer.

Populations experience the fastest growth rate and are first noticed on:

  • Dry sites with sandy soil and abundant oak
  • Mowed lawns with preferred tree species (oak, crabapple, birch, etc.)
  • Large oaks (bur, in particular) with rough bark, especially on or adjacent to mowed lawns
Five small gypsy moth egg tan masses on a single tree branch in Walworth County.

Gypsy moth egg masses found in Walworth County in fall 2021.
Photo Credit: Gypsy moth egg masses KMSU













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Managing Damage By White Pine Weevil

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

Tree damage from white pine weevil is noticeable across Wisconsin this time of year. White pine weevils attack several different Wisconsin species, including eastern white pine, jack pine and spruce.

Adult weevils lay their eggs on terminal leaders in the spring. After the eggs hatch, larvae bore into the terminal and begin feeding downwards just under the bark which can result in the killing of a 1 to 2-feet section of the terminal leader as they feed. Terminal leaders will often have a wilted or “shepherds crook” appearance, and they will turn rusty red to brown late in the fall season. These dead terminal leaders will often break off during the winter.

A white pine tree with a cluster of dead twigs caused by a white pine weevil attack.

Dead terminal leader caused by a white pine weevil attack on a young white pine.
Photo Credit: Wisconsin DNR

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Mystery Walnut Defoliator Identified

Article by: Mike Hillstrom, Forest Health Specialist

In 2020, forest health staff in Wisconsin, Minnesota and Iowa received calls about black walnut stands being defoliated and webbed. In 2021, the defoliation expanded to multiple additional black walnut stands in southwest Wisconsin, while northeast Iowa and Minnesota continued to see damage. Recently, molecular work completed by the Wisconsin Department of Agriculture, Trade and Consumer Protection has identified the larvae causing the damage as a native Tortricid moth, Gretchena amatana.

G. amatana caterpillars on tree.

G. amatana caterpillars on tree.

Fine webbing covers walnut tree trunk.

Fine webbing covers walnut tree trunk.












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