Disease

Rotstop® C No Longer Available In North America

Posted on by akabelowsky
Photo of a worker manually applying fungicide, imbued with blue dye, to a freshly cut tree stump to fight the spread of fungal diseases such as Heterobasidion root disease.

A worker manually applies fungicide, imbued with blue dye, to a freshly cut tree stump to fight the spread of fungal diseases such as Heterobasidion root disease. / Photo Credit: Wisconsin DNR

By Kyoko Scanlon, DNR Forest Pathologist, Fitchburg
Kyoko.Scanlon@wisconsin.gov

The manufacturer, Lallemand Plant Care, recently decided to remove Rotstop® C fungicide from the North American market.

As a result, the product is no longer available for purchase in North America. If you already have the product and have stored it in an appropriate space, you may still use it as a preventative treatment for Heterobasidion root disease (HRD) as long as the expiration date has not arrived.

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Columbian Timber Beetle Fact Sheet Debuts

Posted on by akabelowsky
Photo showing staining, in the shape of a many-pointed star, evident in the cut ends of silver maple logs.

Staining, in the shape of a many-pointed star, is evident in the cut ends of silver maple logs. / Photo Credit: Chris Firgens, Oconto County Forest

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

Columbian timber beetle (Corthylus columbianus) is an ambrosia beetle native to the eastern United States.

In Wisconsin, we have had reports of Columbian Timber Beetle (CTB) attacking silver maple in the northeastern and lakeshore areas of the state, dating back to the early 1990s. The insects have caused significant staining from repeated attacks. In southern Wisconsin, CTB can attack oaks to a lesser degree, including bur, northern red and white oak.

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UW-Madison’s Raffa Talks Trees’ Natural Defenses

Posted on by akabelowsky
Photo of Ken Raffa, professor emeritus with the University of Wisconsin-Madison Department of Entomology.

Ken Raffa, professor emeritus with the University of Wisconsin-Madison Department of Entomology. / Photo Credit: University of Wisconsin-Madison

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

Do you pity the poor tree, forced to stand defenseless against the ravages of insect pests, fungi and disease?

Then, you have not listened to Dr. Ken Raffa discuss the impressive natural defenses trees have developed.

Raffa, a professor emeritus with the University of Wisconsin-Madison’s Entomology Department, recently appeared on Proforest Podforest podcast to discuss the topic “Inside the Tree’s Natural Defense.”

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Resources to Help Urban Foresters Set And Meet Tree Diversity Goals

Posted on by janness

By Shahla Werner, Urban Forestry Council Member and Department of Agriculture, Trade and Consumer Protection Plant Protection Section Manager

Urban foresters are increasingly aware of the importance of tree species, age and size diversity to ensure resilient tree canopy and all the associated benefits in their communities. The 20-10-5 rule, which specifies that no more than 20% of trees planted should be from one family, no more than 10% from one genus and no more than 5% from one species (including cultivars), can be helpful in setting tree diversity goals. Applying these guidelines can provide urban forests some protection against huge losses caused by invasive forest pests. Continue reading “Resources to Help Urban Foresters Set And Meet Tree Diversity Goals” →

Watch For Oak Decline And Mortality This Summer

Posted on by akabelowsky
Oak decline and mortality at Big Foot Beach State Park in 2024.

Oak decline and mortality at Big Foot Beach State Park in 2024. / Photo Credit: Wisconsin DNR

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

Oak decline and mortality continue to be an issue in Wisconsin, and because of the recent droughts and spongy moth outbreak, we expect these impacts to become more widespread this summer.

Forest decline is the progressive loss of tree and stand vigor and health over several years without obvious evidence of a single causal factor. Typically, trees die in a scattered fashion across a large area over several years. The additional stress from defoliation can result in pockets of heavy oak mortality, particularly on dry, sandy sites and steep, rocky ridges and hills.

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Spring Brings Opportunities To Protect Oak Trees

Posted on by akabelowsky
A photo of an oak tree with a branch that has been pruned, but not treated with protective paint to prevent infection with oak wilt.

Pruning, cutting, or wounding oaks during April through July leaves them vulnerable to oak wilt. / Photo Credit: Paul Cigan, Wisconsin DNR

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

With warmer spring weather fast approaching, the Wisconsin Department of Natural Resources (DNR) recommends protecting oaks from the often-fatal disease, oak wilt, by refraining from pruning, cutting or injuring oak trees from April through July.

Oak wilt is a serious disease that kills trees in the red oak group (including pin oak, northern red oak and black oak) and weakens those in the white oak group (bur oak, swamp white oak, white oak and English oak).

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Heterobasidion Root Disease Online Maps Updated

Posted on by akabelowsky
Photo of a tree showing fruiting bodies of Heterobasidion root disease at its trunk.

A tree shows fruiting bodies of Heterobasidion root disease at its trunk. / Photo Credit: Wisconsin DNR

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

Heterobasidion root disease (HRD), a destructive fungal disease, continues to be found in Wisconsin.

The Wisconsin Department of Natural Resources (DNR) has confirmed detections in several stands over recent months.

The DNR’s 6-mile and 25-mile buffer zone maps have been updated based on the locations of the newly confirmed stands. The most notable changes due to expanded buffer zones have taken place in Door, Marinette, Milwaukee and Pierce counties.

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A Wonderful Winter Display: Phomopsis Galls

Posted on by akabelowsky
Phomopsis galls are plentiful on branches of a 120-year-old red oak tree in Clark County, Wisconsin, in 2024.

Phomopsis galls are plentiful on branches of a 120-year-old red oak tree in Clark County, Wisconsin, in 2024. / Photo Credit: Kris Wimme, retired Wisconsin DNR forester

By Alex Hornung, DNR Forest Health Specialist, Plover
Alexandra.Hornung@wisconsin.gov

It is the perfect time of year to be on the lookout for galls – woody growths or swellings on tree branches that are typically oblong in shape and of varying sizes.

They can often be found on small branches, but occasionally they can affect large branches or even the main stem. Galls can occur for several reasons, ranging from fungi to bacteria to insect activity.

One type, Phomopsis gall, can be particularly impressive to see. Galls formed due to this native fungus mostly occur on oak, hickory and maple trees in Wisconsin.

 

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It’s A Good Time To Work On Oak Trees

Posted on by akabelowsky
A person prunes a tree during the winter months.

Winter is an ideal time to perform pruning and trimming work on oak leaves. / Photo Credit: Wisconsin DNR

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

Winter is an ideal time to perform trimming, cutting and brush removal work on and near oak trees.

For one thing, it’s a low-risk period for the trees to be infected with oak wilt, a fungal disease spread by beetles. When a red oak is infected with oak wilt, it will die that year; the disease also stresses trees in the white oak group, often fatal with bur oaks and swamp white oaks.

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Tree Disease Maps Have Migrated

Posted on by akabelowsky
The Wisconsin web map for Heterobasidion root disease, available through ArcGIS Online.

The Wisconsin web map for Heterobasidion root disease, available through ArcGIS Online. / Map Credit: Paul Cigan, Wisconsin DNR

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

The Wisconsin Department of Natural Resources (DNR) Forest Health program hosts two interactive web maps on its webpage:

Heterobasidion Root Disease

Oak Wilt Seasonal Harvesting Opportunities

Continue reading “Tree Disease Maps Have Migrated” →