Pest

Dropping Leaves May Indicate Oak Wilt

Posted on by akabelowsky

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

Photo showing that oak leaves that drop from a tree infected with oak wilt may be all brown or all green, or often they will have green near the base of the leaf and the outer portions will be brown or watersoaked green.

Oak leaves that drop from a tree infected with oak wilt may be all brown or all green, or often they will have green near the base of the leaf and the outer portions will be brown or watersoaked green. / Photo Credit: Linda Williams, Wisconsin DNR.

The middle of summer is the time to start watching oak trees for symptoms of oak wilt. Although symptoms show up suddenly and leaves drop quickly, symptoms can emerge anytime between now and when leaves turn color in the fall.

Trees that were wounded in the spring and became infected with the fungus that causes oak wilt will usually die that same year. In established oak wilt pockets, the fungus moves underground through grafted root systems and trees will wilt as the fungus moves into the tree.

Continue reading “Dropping Leaves May Indicate Oak Wilt” →

Tubakia Leaf Disease Affects Red Oak

Posted on by akabelowsky

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

A tree showing that lower branches are thin and have lost leaves due to Tubakia leaf spot, while leaves on its upper branches look good.

A tree showing that lower branches are thin and have lost leaves due to Tubakia leaf spot, while leaves on its upper branches look good. / Photo Credit: Linda Williams, Wisconsin DNR.

Tubakia leaf spot is a leaf disease caused by a fungus (Tubakia dryina) that typically affects the lower canopy of red oaks.

Because of all the rain that came during the spring and early summer of 2024, the fungus has started to impact some trees. Problems didn’t occur last year because the weather was too dry.

Continue reading “Tubakia Leaf Disease Affects Red Oak” →

Emerald Ash Borer Confirmed In All 72 Counties

Posted on by akabelowsky

By Art Kabelowsky, DNR Outreach and Communications, Fitchburg;
Arthur.Kabelowsky@wisconsin.gov; 608-335-0167

Closeup photo of an adult emerald ash borer. The pest has been detected in Burnett County, making it the 72nd and final county in Wisconsin that have confirmed presence of the invasive insect.

The emerald ash borer has been detected in Burnett County, making it the 72nd and final county in Wisconsin that have confirmed presence of the invasive insect. / Photo Credit: Paul Cigan, Wisconsin DNR

Sixteen years after the Wisconsin Department of Natural Resources (DNR) first detected emerald ash borer (EAB) in Wisconsin, the invasive beetle has been found in the last county without a previous detection.

Burnett County, in northwest Wisconsin, is the 72nd and final county to have a detection of the tree-killing pest.

Continue reading “Emerald Ash Borer Confirmed In All 72 Counties” →

Basswood Trees Short On Leaves Due To Thrips

Posted on by akabelowsky

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

Photo showing Basswood leaves that have been damaged due to the feeding of introduced basswood thrips.

Basswood leaves show damage due to the feeding of introduced basswood thrips. / Photo Credit: Linda Williams, Wisconsin DNR

For the third consecutive year, damage from introduced basswood thrips (Thrips calcaratus) is significant in some areas of northeast Wisconsin, especially Forest County.

Introduced basswood thrips are tiny, invasive insects that feed inside tree buds in early spring. The feeding causes leaves to deform when they expand, looking like they suffered frost or wind damage.

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Oak Moth Outbreaks May Have Peaked In North

Posted on by akabelowsky

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

Wide-angle photo showing many oaks across northern Wisconsin with partially defoliated, thin, and yellow-tinted crowns caused by defoliation from the oak leafroller and oak leaftier.

Many oaks across northern Wisconsin displayed partially defoliated, thin, and yellow-tinted crowns caused by defoliation from the oak leafroller and oak leaftier. / Photo Credit: Paul Cigan, Wisconsin DNR

A three-year-long outbreak of oak leafroller moth and oak leaftier moth—two native, early-season oak defoliators—continued this spring in northern Wisconsin, leaving behind tens of thousands of acres of oak-dominated forest with scattered, widespread defoliation.

Partially defoliated, thin and yellow-tinted crowns were visible across portions of Barron, Rusk, Sawyer and Washburn counties, as well as areas in Florence, Forest, northern Marinette and Vilas counties.

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Pruning Can Control White Pine Blister Rust

Posted on by akabelowsky

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

Eastern white pines (Pinus strobus) can be beautiful trees in urban and forested areas (they can tower above the rest of the forest’s trees), but they can also attract a deadly disease.

White pine blister rust (Cronartium ribicola), also known as WPBR, is a fungus that can attack branches and the main stem of white pine, causing cankers that continue to grow each year and creating dead spots that can girdle branches or the main stem. Damage from a girdling canker may take years to become severe enough to cause tree decline and mortality. That means you may be able to help your trees and prevent mortality.

Continue reading “Pruning Can Control White Pine Blister Rust” →

Spongy Moth Egg Mass Surveying Video Released

Posted on by akabelowsky

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

The Wisconsin Department of Natural Resources (DNR) Forest Health team joined with the DNR Office of Communications to produce an instructional video aimed at helping large landowners and land managers in the fight against spongy moth.

The video, less than 2 minutes in length, shows how to conduct a survey of spongy moth egg masses in the fall. With that information, people can predict how much damage to expect from the caterpillars in the spring, giving them time to make advance plans for the most effective control options.

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DNR Debuts Fact Sheet On Twolined Chestnut Borer

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

The Wisconsin Department of Resources (DNR) has debuted a new Forest Health fact sheet on twolined chestnut borer (Agrilus bilineatus), a native beetle that attacks already weakened oaks in Wisconsin.

Continue reading “DNR Debuts Fact Sheet On Twolined Chestnut Borer” →

Spongy Moth Resource Center Hatches Just In Time

Posted on by akabelowsky

By Art Kabelowsky, DNR forest health communications and outreach specialist, Fitchburg
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

A screenshot of the mock-up of the new Spongy Moth Resource CenterAs Wisconsin braces for another potentially busy season of spongy moth caterpillars, three state agencies have teamed up to make it easier for tree owners and others to access the latest information and advice on the invasive, leaf-chomping pests.

The Wisconsin Department of Natural Resources (DNR) has joined the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) and the University of Wisconsin-Madison Extension to revamp the state’s interagency spongy moth information webpage.

Renamed the “Spongy Moth Resource Center,” a first glance at the document reveals basic information on the insect. But by following a new list of “Frequently Asked Questions,” visitors can tunnel deeper to more easily find information that applies specifically to their situation.

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Emerald Ash Borer Detected In Washburn, Taylor Counties

Posted on by akabelowsky

By Paul Cigan, DNR forest health specialist, Hayward;
Paul.Cigan@wisconsin.gov or 715-634-9232

Photo of an emerald ash borer on a tree

The emerald ash borer was detected in the Wisconsin counties of Taylor and Washburn in April, making them No. 70 and No. 71 of Wisconsin’s 72 counties that have confirmed presence of the invasive insect.

The emerald ash borer (EAB) has been detected for the first time in Washburn and Taylor counties, making them the No. 70 and No. 71 of Wisconsin’s 72 counties to have a confirmed detection of the invasive insect.

Here are the details of the most recent discoveries: Continue reading “Emerald Ash Borer Detected In Washburn, Taylor Counties” →