Invasive plant

Giant Hogweed Or Cow Parsnip?

By Jaqi Christopher, DNR Forest Invasive Plant Specialist, Rhinelander, Jacquelyn.christopher@wisconsin.gov

Giant hogweed is a large invasive species commonly confused with the native look-alike cow parsnip. Although giant hogweed is uncommon in Wisconsin, it’s important to know the difference between the two.

Person standing with giant hogweed towering over them.

Giant hogweed can invade woodlots and get 8-20 feet tall. Photo Credit: Ramona Shackleford

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April Showers Bring May Garlic Mustard

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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Understanding The Extent Of Invasive Species And Other Urban Forest Challenges

By Dan Buckler, DNR Urban Forest Assessment Specialist, Madison, daniel.buckler@wisconsin.gov or 608-445-4578

How extensive are buckthorn and other invasive species in our communities? We don’t know yet, but Wisconsin’s Urban Forest Inventory And Analysis (UFIA) project will be able to answer that and many other questions.

Buckthorn beneath dead ash trees at Big Foot Beach State Park. Photo by Bill McNee.

Besides simple stem counts, we can learn about the type of land where buckthorn is found, species under which buckthorn is growing and trends in invasive species expansion or decline over time.

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Upcoming Webinars: EAB University And TREE Fund

The EAB University Spring 2022 Webinars are right around the corner. All webinars are free, and many count towards continuing education programs.

Can’t watch them live? No problem! All webinars are recorded and posted afterward.

Check out the EAB University Spring 2022 webinars and register for them here. All sessions begin at 10 a.m. CST.

  • Feb. 24: The Biology and Management of the Invasive Spotted Lanternfly. Holly Shugart, Ph.D. Postdoctoral Scholar, Pennsylvania State University
  • March 1: Firewood Rules, Certifications, and Recommendations across the USA.
    Leigh Greenwood, Forest Health Program Director, North America Region, The Nature Conservancy 
  • March 3: The Worst Kind of Snowbird: The Invasion of Asian Longhorned Beetle in South Carolina. David Coyle, Assistant Professor and State Extension Specialist, Clemson University 

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Garden Planning – Avoid Invasive Plants

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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Fighting Invasive Plants

Invasive plants are a major threat to Wisconsin’s forests, highlighted in the forest health chapter of Wisconsin’s Forest Action Plan. Invasive plants limit tree regeneration, reduce plant diversity and increase management costs. Recent Forest Inventory and Analysis data from the USDA Forest Service found that more than half of forest sites surveyed in Wisconsin had two or more invasive plant species. Forest landowners should learn to recognize common invasive plants like buckthorns, honeysuckles and garlic mustard. Mobile applications are a handy tool for landowners to learn to identify the plant species in their woods (e.g., PlantNet, iNaturalist) and report invasives (e.g., EDDMapS). For information about the regulated invasive plants in Wisconsin visit the Wisconsin Department of Natural Resources’ (DNR) Terrestrial Invasive Species page.

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Forest Health In The Statewide Forest Action Plan

The forest health chapter of Wisconsin’s 2020-2030 Statewide Forest Action Plan, completed in June 2020, highlights the impacts of insects, diseases, invasive plants and worms in Wisconsin’s forests.

Forest health experts from government agencies, universities and tribes worked together to evaluate these current impacts. They then developed goals and strategies to help the forestry community refine how it will invest state, federal and partner resources to address major forest health management and landscape priorities over the next ten years.

Forest health is a critical component of the plan because native and non-native pests increase tree mortality to a level that negatively affects forest stocking levels, clean water, wildlife habitat and raw material for wood products. This causes economic losses and undesirable management outcomes. Continue reading “Forest Health In The Statewide Forest Action Plan”

Got Buckthorn?

Article By: Jaqi Christopher, DNR Forest Invasive Plant Specialist, Rhinelander, Jacquelyn.Christopher@wisconsin.gov

Common buckthorn with green leaves and dark purple/black berries.

Common Buckthorn leaves with berries. Notice the prominent leaf veins and small thorns at the end of the branches.
Photo Credit: Wisconsin DNR

You can find buckthorn just about anywhere these days. It can sneak into the tidiest of gardens, as well as woodlots and forests. It aggressively outcompetes native plants and even tricks wildlife into spreading it to new areas. For example, birds are enticed to eat the berries, but buckthorn berries have a laxative effect, robbing birds of nutrition and ensuring the seeds are spread quickly across the landscape. 

There are two species of buckthorn in the state: common buckthorn and glossy buckthorn. The plants are similar in appearance and equally harmful to native ecosystems. Common buckthorn and glossy buckthorn grow to be 20-25 feet tall. Glossy buckthorn has round, glossy leaves with prominent leaf veins and a smooth margin, while common buckthorn has dull green leaves with small teeth on the margin. The branches of common buckthorn will have a small thorn at the tip of the twig. The bark is similar in both species, being rough and flakey. Native cherry and plum trees have similar bark, but buckthorn can be identified by leaf appearance andby cutting into the bark to expose the bright yellow and orange wood underneath.

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Oriental Bittersweet: A Bitter Beauty!

Article By: Jaqi Christopher, Invasive plant specialist & Mary Bartkowiak, Invasive plant coordinator

Just as the leaves begin to shift from summer green to the fall shades of gold, orange, red and bronze, the fruits of Oriental bittersweet explode on the scene with their very own show-stopping colors of bright gold and red.

The sight of these vines full of colorful berries may tempt the casual observer to take these berry-filled branches home to use as fall decorations or to plant in their own garden. This, however, would be a mistake, as this striking plant is a serious threat to native ecosystems. Oriental bittersweet is a restricted species under Wisconsin’s Invasive Species Rule NR40. This makes it illegal to transport, transfer or introduce Oriental bittersweet statewide.

Oriental bittersweet is an aggressive-growing woody vine that invades forests, woodlands, fields and hedgerows. The vines twine up trees, smother the crown and girdle trunks with their thick woody stems. In fact, the sheer weight of the vine can cause tree crowns to break and collapse and whole trees to uproot. Additionally, large mats of bittersweet can shade out native plants.

Oriental bittersweet woody vine twines up tree, girdling tree trunk

Oriental bittersweet vine girdles tree trunks. Photo Credit: Minnesota Department of Agriculture

Oriental bittersweet woody vine twines up tree, girdling tree trunk

Oriental bittersweet vine girdles tree trunks. Photo Credit: University of Illinois’ Chris Evans

 

 

 

 

 

 

 

 

 

 

 

 

 

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Invasive Plant Management Factsheets

Tree-of-Heaven. Photo credit: Richard Gardner, Bugwood.org

The Renz Lab at the University of Wisconsin-Madison Division of Extension has created a series of factsheets discussing the identification and control of many common invasive plant species problematic to natural areas.

Mechanical, cultural and chemical control methods are discussed in detail, including the effectiveness of the control method and appropriate rates and timings of chemical control applications.

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