Forest Health News

Blue ash: Wisconsin’s little-known ash tree

By Bill McNee, forest health specialist, Oshkosh, Bill.Mcnee@wisconsin.gov, 920-360-0942

Many people interested in trees know about Wisconsin’s white, green and black ash species. However, there’s a fourth species that fewer people know about. Blue ash, Fraxinus quadrangulata, occurs naturally only at a few sites in Waukesha County. It can easily be identified by the cork ridges on the twigs, which give them a four-sided, square appearance. The tree was given its name because of the blue dye that is produced by soaking the inner bark in water.

Four-sided, square twig of a blue ash. Photo by Bill McNee.

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“Spring” into action with invasives in focus

By Paul Cigan, plant pest and disease specialist, Paul.Cigan@wisconsin.gov, 715-416-4920

One of the most amazing aspects of living in Wisconsin, with its four seasons of ever-changing natural beauty, is the re-awakening of plant life every spring. Whether you’re a gardener, sportsperson or casual observer on a walk, it’s hard to overlook the floral sea of white trilliums, the bee-frenzied blooms of a crabapple, or even the mere greening up of turf grass. These spring advances usher in a sense of re-awakening of a sleepy plant world and assure us that summer will once again come.

While recently out on a spring hike in northern Wisconsin, my eyes were drawn to the bright green glow of emerging understory plants. Making my way closer, my initial excitement was offset by the disappointment of seeing what I quickly realized was in fact garlic mustard—an increasingly common and problematic exotic, invasive understory plant. Although garlic mustard is perhaps the “poster” plant for invasive plant awareness, the unfortunate reality is that it is just one of hundreds of invasive species that continue to spread into our forests.

The spring green-up of garlic mustard may look pretty but this invasive species is not good news for Wisconsin forests or the people who manage them. Credit: Duluth CISMA.

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Preliminary findings are promising first step in control of jumping worms

By Bernie Williams, plant pest and disease specialist, Bernadette.Williams@wisconsin.gov, 608-444-6948

Invasive earthworms in the genus Amynthas, more commonly known as “jumping worms,” were first identified in Dane County in 2013 and have since been reported in 45 of the state’s 72 counties. Verified species in Wisconsin are Amynthas tokioensis, A. agrestis, and the closely related Metaphire hilgandorfi, first identified in September 2017. A. tokioensis is the most common of the three species. A. agrestis typically appears in combination with A. tokioensis but rarely on its own.

Adult jumping worms are identified by their dark brown color and smooth, milky-white band near head.

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Tree-killing fungus investigated at Kettle Moraine State Forest

By Kyoko Scanlon, forest pathologist, Kyoko.Scanlon@wisconsin.gov, 608-235-7532 and Mike Hillstrom, forest health specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov, 608-513-7690

Less than a one-hour drive from Milwaukee, Kettle Moraine State Forest – Southern Unit (KMSU) offers more than 22,000 acres of glacial hills, kettles, lakes, prairie restoration sites, pine woods and hardwood forests. KMSU is one of Wisconsin’s most visited state properties with over 100 miles of mountain biking, horseback riding, snowmobiling and hiking trails. In addition to its ecological and recreational value, KMSU remains a productive and sustainable forest that supports the forest products industry in southern Wisconsin.

Aerial view of KMSU including Ottawa Lake on left.

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Educational HRD video now available

By Kyoko Scanlon, forest pathologist, Kyoko.Scanlon@wisconsin.gov, 608-235-7532

The Wisconsin DNR recently created a short video on Heterobasidion root disease (HRD) to compliment the updated guidelines that were released in 2019. The 5-minute educational video covers HRD biology, its significance as a tree disease, signs and symptoms, as well as preventative measures that landowners can take to reduce its introduction and spread. This is a great video for forestry professionals, landowners and the general public to learn more about HRD. Continue reading “Educational HRD video now available”

USDA seeks ash trees to battle EAB

Emerald ash borer (EAB) is an invasive insect from Asia that was first introduced into the United States in 2002. Since its discovery, EAB has caused the death and decline of tens of millions of ash trees. Today, the U.S. Department of Agriculture (USDA) is using ash trees against the pest to help preserve and protect the tree species. Staff in the USDA EAB biological control (biocontrol) program are asking Wisconsin landowners in Sheboygan, Fond du Lac and Door counties to help by donating infested ash trees for use in raising wasps that attack and kill EAB.

A square window of bark is removed from green ash to uncover EAB larvae underneath.

USDA staff cut a “bark window” in green ash to uncover signs of EAB.

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Proposed guidance available for public comment

By Bill McNee, forest health specialist, Oshkosh, Bill.Mcnee@wisconsin.gov, 920-360-0942

The DNR Forest Health Program currently has proposed guidance, “Organizing an aerial spray for forest pests: Recommendations and regulations,” available for public comment until May 25. The document can be found on the proposed DNR program guidance webpage under “new proposed program guidance.” Comments can be submitted through this webpage.

Cover page of proposed aerial spray guide.

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DATCP pesticide certifications during COVID-19

By Becky Gray, forest health team leader, Fitchburg, Rebecca.Gray@wisconsin.gov, 608-220-3022

Due to COVID-19, the Department of Agriculture, Trade and Consumer Protection (DATCP) is extending pesticide certifications. If your pesticide certification will expire between January 31st and September 30th, then your certification is now valid until October 31st. Please refer to DATCP’s press release for more details.

If you were planning to take the test for pesticide certification this spring, DATCP is offering online pesticide exams for certain categories, including Forestry Category 2.0. The online exams are only for a temporary pesticide applicator certification which will be good until October 31st. Please refer to DATCP’s press release explaining the online pesticide exams for more information.

Two-lined chestnut borer in flooded oak stands

By Mike Hillstrom, forest health specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov, 608-513-7690

2019 was the wettest year ever recorded in Wisconsin. Four of Wisconsin’s top five wettest years have taken place in the last decade, three of them in the last five years: 2019, 2018 and 2016. Flooding can be stressful for trees, and with flooding occurring over the past few years in many parts of the state, forest health staff expect the impacts to forests to continue to escalate. Continue reading “Two-lined chestnut borer in flooded oak stands”

White pine blister rust can girdle branches

By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665

White pine branches that suddenly turn red may be a sign of white pine blister rust. White pine blister rust is a fungal infection that creates expanding “dead spots” or cankers on the branches or main stem of host trees. Eventually the fungus grows enough to girdle the branch or main stem and the needles fade from green to pale green to rusty red. Orange, spore-producing pustules erupt around the edges of the canker in the spring.

Orange pustules erupt through the bark and around the margins of a white pine blister rust canker. Photo by Jean Romback-Bartels.

Orange pustules erupt through the bark and around the margins of a white pine blister rust canker. Photo by Jean Romback-Bartels.

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