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Oak Leaf Issues That Are Not Oak Wilt

Closeup photo showing oak wilt leaf symptoms on a red oak leaf. Leaves often show browning on the outer portions of the leaf while the base of the leaf will still have some normal green color.

Oak wilt leaf symptoms on a red oak leaf often show browning on the outer portions of the leaf while the base of the leaf will still have some normal green color. / Photo Credit: Wisconsin DNR

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

Oak wilt symptoms are active right now, but so are several other oak issues that may be mistaken for oak wilt.

Issues including Tubakia leaf spot, mite damage and leaf scorch are all causing problems in northern Wisconsin and may be mistaken for oak wilt.

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Which Witches’ Broom Is It?

Witches’ broom on serviceberry. The leaves of this infected shrub are dying because of prolific spore production on their undersides. / Photo Credit: Wisconsin DNR

By Tim Shively, DNR Forest Health Specialist, Eau Claire
Tim.Shively@wisconsin.gov or 608-772-6974

Witches’ broom is a term that describes a disease of many different plants. It’s a distinctive, abnormal growth typically caused by a pathogen — though in some cases it can result from insect feeding.

The namesake symptom appears as abnormally dense clusters of stunted shoots, branches, and foliage that strongly resemble a witch’s broom from storybooks and folklore. In Wisconsin, this is not often a critical forest health concern that merits management action, but Wisconsin Department of Natural Resources Forest Health staff recently observed widespread incidence of two particular witches’ broom diseases.

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Periodical Cicada Damage Still Visible In Some Areas

Photo showing dieback discovered on red cedar branches in Beloit (Rock County) in August 2025.

Dieback discovered on red cedar branches in Beloit (Rock County) in August 2025. / Photo Credit: Wisconsin DNR

By River Mathieu, DNR Forest Health Specialist, Fitchburg
River.Mathieu@wisconsin.gov or 608-772-2758

In August, random branch dieback was observed by a Wisconsin Department of Natural Resources forester on red cedars in a 10-acre stand near Beloit in Rock County.

At first, the pattern of dieback was perplexing. Based on a photograph, the damage was first presumed to be caused by a fungal disease. Once a site visit was conducted, it was determined that the branch dieback was caused by cicada oviposition (egg-laying) damage from last year’s emergence of periodical cicadas.

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DNR, UW Offer Fall Invasive Plants Workshops

Buckthorn beneath dead ash trees at Big Foot Beach State Park. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

Is buckthorn taking over your urban property? Would you like to be able to determine which plants are doing harm to the native landscape? Are you ready to arm yourself in the fight against invasives?

If so, this day-long workshop is for you!

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Urban Forestry Grants Webinar Announced: Updated Application Process

The Wisconsin Department of Natural Resources (DNR) is hosting a webinar to help you develop a competitive urban forestry grant application. This webinar will guide you through the application form so you can submit a strong application that aligns with the DNR’s Urban Forestry Program funding priorities.

Register today to reserve your spot in the upcoming webinar. After registering, you will receive a confirmation email containing information about joining the webinar. Continue reading “Urban Forestry Grants Webinar Announced: Updated Application Process”

The DNR Reforestation Program Needs Seeds

By Jeremiah Auer, DNR Regeneration Specialist; Jeremiah.Auer@wisconsin.gov

The DNR’s Reforestation Program needs red and white pine cones – more specifically, we need the seeds found within those cones for our reforestation needs. The Reforestation Program produces millions of pine seedlings every year at the Wilson State Nursery in Boscobel, and the only way we can produce those seedlings is with seed collected from the fields and forests of Wisconsin. Continue reading “The DNR Reforestation Program Needs Seeds”

American Forests Launches Tree Equity Coaching Network

American Forests LogoThe  American Forests National Coaching Network is a community for urban foresters, community advocates, city leaders and allied professionals to connect, learn, inspire and cultivate city commitments to advance tree equity. This network is a way for people to address challenges and build their tools and resources. Continue reading “American Forests Launches Tree Equity Coaching Network”

Invasive Plant Japanese Stiltgrass Detected In Rock County

A wide-angle photo showing a mat of Japanese stiltgrass growing in Rock County, Wisconsin, in July 2025.

A mat of Japanese stiltgrass growing in Rock County, Wisconsin, in July 2025. / Photo Credit: John Zaborsky, University of Wisconsin-Madison Renz Weed Science Lab

By Wisconsin DNR

The harmful invasive plant Japanese stiltgrass (Microstegium vimineum) has been detected in a private woodland near Beloit in Rock County, according to a blog post made Monday by the University of Wisconsin-Madison Extension.

It is the second detection of the non-native annual grass in Wisconsin. The first took place in 2020, inside the Coulee Experimental Forest in La Crosse County. The Wisconsin Department of Natural Resources  (DNR) has been working to eradicate that population.

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Monitor Your Trees For Spongy Moth-Related Decline And Mortality

A photo taken June 20, 2025, shows dead and dying oaks near Whitewater Lake in Walworth County, following a period of defoliation and summer drought.

A photo taken June 20, 2025, shows dead and dying oaks near Whitewater Lake in Walworth County, following a period of defoliation and summer drought. / Photo Credit: Wisconsin DNR

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

Property owners are encouraged to monitor their trees for signs of decline and mortality, as the last few years have been marked by drought and spongy moth defoliation.

Landowners who have oak, birch, crabapple, aspen, willow, tamarack and basswood (linden) trees should be particularly watchful, because the caterpillars of this invasive insect prefer these species. Many other tree species are not preferred by the caterpillars and are less likely to be heavily defoliated, but are more likely to die if heavy defoliation should happen.

This article focuses on oak impacts.

The 2021-24 spongy moth outbreak has now collapsed statewide; no defoliation has been observed as of late July 2025. Only a few reports of single caterpillars were received by Wisconsin DNR Forest Health staff. (Note: Parts of Wisconsin may be experiencing a continuing outbreak of different caterpillars known as “oak leafroller” and “larch casebearer.”)

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Avoid Ash Trees When Placing Deer Stands

Photo showing a Wisconsin hunter climbing into his tree stand.

A Wisconsin hunter climbs into his tree stand. The Wisconsin Department of Natural Resources urges hunters to avoid placing their stands on or near ash trees because the trees may experience breakage of stems or branches due to damage from the emerald ash borer. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

It’s time for deer hunters to begin scouting properties to identify potential locations for their deer stands this hunting season.

The Wisconsin Department of Natural Resources (DNR) cautions hunters to avoid placing deer stands in or near ash trees – a practice that presents a clear safety hazard.

Most ash trees in the southern two-thirds of Wisconsin are dead or dying due to the emerald ash borer (EAB), and infestations in the northern part of the state are rapidly expanding. Some areas already experience decline and mortality of ash trees. EAB has been confirmed present in all 72 Wisconsin counties, and unreported infestations are also likely to be present.

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