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Spring Cleaning: Storm Damage Cleanup Brings Oak Wilt Risk

Posted on by brenna.denamur

By Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665 & Paul Cigan, DNR Forest Health Specialist, Hayward, Paul.Cigan@wisconsin.gov, 715-416-4920.

Spring cleanup is always a busy time in the Northwoods as those with second homes and cabins make the trek northward to prepare for a summer of fun. For many, this will mean cleaning up trees and branches damaged by winter storms.

A forested scene with broken branches at the base of a white pine tree.

Large white pines (pictured here) and young birch growing on forest edges were most heavily impacted by winter’s storms. Photo: Wisconsin DNR

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April Showers Bring May Garlic Mustard

Posted on by brenna.denamur

By Brenna DeNamur, DNR Forest Health Outreach Specialist, Madison, Brenna.DeNamur@wisconsin.gov; Jaqi Christopher, DNR Forest Invasive Plant Specialist, Rhinelander, Jacquelyn.Christopher@wisconsin.gov; & Mary Bartkowiak, DNR Forest Invasive Plant Coordinator, Rhinelander, Mary.Bartkowiak@wisconsin.gov

Spring is here! Invasive plants, like garlic mustard, are often among the first green life to emerge in the new season.

A dense population of garlic mustard carpets a forest floor.

Garlic mustard is an invasive plant that appears early in spring. Photo: Wisconsin DNR

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Thousand Cankers Disease Update

Posted on by brenna.denamur

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

Upward view of a large, leafless black walnut tree.

Black walnut is one of Wisconsin’s healthiest, least threatened tree species. Photo: Wisconsin DNR

Once in a while, the Wisconsin DNR Forest Health Team gets to deliver good news about an emerging insect or disease issue!

Recent research suggests that thousand cankers disease of walnut is not the threat we initially feared when cases appeared for the first time in the eastern U.S. in 2010. Thousand cankers disease is caused by walnut twig beetles carrying a fungal pathogen. The disease has yet to be detected in Wisconsin.

Following its arrival in the eastern United States, the insect’s populations declined. Many stressed urban trees recovered after drought conditions subsided in the impacted areas, and forest trees have fared even better than their urban counterparts. Additionally, walnut twig beetles don’t enjoy Wisconsin winters, as mortality begins in the low single digits Fahrenheit. Perhaps this is why we have not yet found the walnut twig beetle in Wisconsin.

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Emerald Ash Borer Found In Bayfield County

Posted on by brenna.denamur

By Paul Cigan, DNR Forest Health Specialist

Paul.Cigan@wisconsin.gov or 715-416-4920

Emerald ash borer (EAB) has been discovered in Bayfield County for the first time in both the city of Bayfield and Bayview township to the south. This marks the 63rd out of Wisconsin’s 72 counties to have an EAB discovery since its initial detection in 2008.

Dead white ash with woodpecker damage in a park

Figure 1: First known infested ash tree in Bayfield County with characteristic woodpecker damage (i.e., flecking).
Photo: Wisconsin DNR

Several white ash trees (Fig 1.) were observed in and around a roadside park in the city of Bayfield, and larval specimens were subsequently lab-confirmed. In Bayview, a black ash swamp had several infested black ash (Fig 2). 

After introduction, EAB populations remain low for at least several years as most larvae in newly infested, healthy ash require two years to complete their life cycle. The abundance of healthy ash at each site suggests EAB populations have remained low since their introduction at least three years ago. However, EAB will kill ash more quickly as beetle numbers mount and more larvae transform from egg to adult in a single year. Unfortunately, many ash in the area are expected to die within four to seven years based on detection-to-impact timeframes observed from the Superior and Duluth area and research conducted in midwestern states. Continue reading “Emerald Ash Borer Found In Bayfield County” →

Help Protect Oak Trees From Oak Wilt

Posted on by brenna.denamur

Contact: Paul Cigan, DNR Forest Health Specialist

Paul.Cigan@wisconsin.gov or 715-416-4920

As April brings a high risk of the often-fatal oak wilt disease, the Wisconsin Department of Natural Resources (DNR) recommends not pruning or cutting oaks from April through July.

A large oak tree in a wooded area has fresh wounds from branches being sawed off.

Do not prune, cut or wound oaks April through July.
Photo: Linda Williams

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Squirrel Damage Mayhem

Posted on by brenna.denamur

By Linda Williams, DNR Forest Health Specialist, Woodruff

Linda.Williams@wisconsin.gov or 920-360-0665

Finger pointing at tooth marks on the wood of a maple that squirrels stripped of bark.

Narrow grooves are left when squirrels chew the bark off a young tree or a branch.
Photo: Wisconsin DNR

In late winter, it’s common to see tree branches that have been freshly stripped of their bark. Damage can be extensive where entire branches, and sometimes entire small trees, can be stripped of bark. This damage, believe it or not, is from squirrels! While primarily found on sugar maples, you can also find squirrel damage on red maples and the occasional oak. So far this year, the damage has been noted in Langlade, Shawano, Oneida and Vilas Counties. 

On sunny days, the pale wood of branches where the bark has been stripped off stands out in the forest. 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 entirely girdled will continue to grow, and callus tissue will begin to grow over the wounds. If branches are nearly girdled, they may leaf out in the spring only to have the leaves suddenly wilt and die as hot weather hits because the tree can’t move enough water to keep the leaves alive. Continue reading “Squirrel Damage Mayhem” →

Protect Your Valuable Ash Trees Against Emerald Ash Borer

Posted on by brenna.denamur

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

Property owners with healthy, valuable ash trees are encouraged to treat them with insecticide this spring to protect against emerald ash borer (EAB). The pest is currently the most damaging threat to trees in Wisconsin, killing more than 99% of the ash trees it infests.

Ash tree branch in West Allis has been damaged by woodpeckers. Sections of bark are missing or have been flecked away.

This ash tree branch in West Allis has been damaged (“flecked”) by woodpeckers feeding on EAB larvae under the bark.
Photo: Bill McNee, Wisconsin DNR

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One Last Chance To Treat Or Remove Spongy Moth Egg Masses; DATCP Slow-The-Spread Aerial Treatments Announced

Posted on by brenna.denamur

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

Three tan-colored lumps about the size of a nickel or a quarter are 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

Spongy moth* (formerly known as gypsy moth) egg masses typically begin to hatch in April as temperatures warm. Now is a great time to inspect your trees for egg masses and treat or remove any masses within reach. Each mass that hatches may produce up to 1,000 leaf-eating caterpillars.

Populations of spongy moths increased in 2020 and 2021 due to favorable weather conditions. This winter’s temperatures have not been cold enough to cause heavy egg mortality. A large rise in caterpillar numbers can be expected in 2022 if weather conditions are warm and dry over the next few months.

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

Posted on by brenna.denamur

By Linda Williams, WI DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov 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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Garden Planning – Avoid Invasive Plants

Posted on by brenna.denamur

By Jaqi Christopher, DNR Forest Invasive Plant Specialist, Rhinelander, Jacquelyn.Christopher@wisconsin.gov and Mary Bartkowiak, DNR Forest Invasive Plant Coordinator, Rhinelander, Mary.Bartkowiak@wisconsin.gov

With winter in full swing, many gardeners dream of spring and begin planning what plants to add to their gardens. Now is a great time to brush up on what not to plant to avoid invasive species that might be hiding in plain sight.

Woodlot in fall, most trees have lost their leaves which are covering the ground. Several burning bush shrubs still with their bright red leaves stick out against the brown backdrop.

Burning bush as a forest invasive.
Photo: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

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