A woman pulls invasive species in a green forested area.
Invasive Species Garlic mustard and other invasive species can hurt people and wildlife and cost millions of dollars each year to control. © Samantha Christian

Stories in Wisconsin

Weeds at Their Worst: Combating Invasive Species

Invasive species in Wisconsin cause trouble for people and wildlife. Here's how we're helping.

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Some of Wisconsin's invasive species sound like science-fiction. There's the bamboo-like plant that's strong enough to crack building foundations and pavement.  Then there's the parsnip that makes your skin photo-sensitive when you brush against it and burns when exposed to sunlight. And don't forget about the aquatic plant that will ruin your day at the lake by getting caught in your boat propeller and make swimming nearly impossible.

Invasive, non-native species such as Japanese knotweed, wild parsnip and Eurasian water milfoil not only make people’s lives miserable, they cause serious damage to Wisconsin’s natural lands and waters. They out-compete native plants, replacing the food and cover that wildlife species depend on. The threat they pose is second only to the direct destruction of habitats through development.

All of Wisconsin’s native habitats—freshwater and terrestrial—are threatened by invasive species.

Invasive Species 101 (2:43) Why are invasive species so bad? Watch this video to learn how invasive species got here, why they’re such a nightmare for our native plants and animals, and what you can do to help stop their spread.

State agency spending topped $5.1 million in fiscal year 2019 to manage Wisconsin’s invasive species, according to a report to the Wisconsin Legislature. State funding was supplemented by additional investments made by nonprofits, local units of government, and by volunteers who donated their time.

What The Nature Conservancy Is Doing about Invasive Species

The Nature Conservancy works to prevent and control the spread of invasive species in Wisconsin, throughout the United States, and in many countries around the world. Together with our partners we focus on:

  • Preventing future introductions & invasions of non-native invasive species
  • Quickly detecting and responding to new populations of invasive species when they occur
  • Protecting native habitats by minimizing the damage caused by invasive species that are challenging or impossible to eradicate
Graphic showing why you should use a boot brush to rid your boots of invasive species.
Boot Brush Sign We’ve installed boot brushes at our preserves so visitors can brush invasive species seeds off their shoes before entering the preserve..

Boot Brushes Help Stop the Spread of Invasive Species

We’ve installed boot brushes so visitors can leave invasive species behind when they enter the preserve. We added sign translations in Spanish and Hmong to reach more preserve visitors.

Our invasive species work extends across a variety of disciplines in Wisconsin. 

Wisconsin Land Management

The Nature Conservancy staff and volunteers actively control invasive species at our Wisconsin preserves through the careful application of controlled fire and herbicides, grazing, mowing and hand pulling.


TNC staff serve on the Wisconsin Invasive Species Council and provide scientific information about invasive species issues to State Agencies, legislators and other decision-makers.

Invasive Species Science

At our Lulu Lake Preserve in southeast Wisconsin, we have worked with scientists to test new techniques to help native aquatic plants compete with Eurasian water milfoil and control invasive cattails.

Partnerships in Wisconsin

TNC joins state and federal agencies and a variety of private and non-profit groups to combat invasive species in Wisconsin.

  • In 2001, TNC joined a group of citizens concerned about invasive plants to help create the Invasive Plants Association of Wisconsin (IPAW). IPAW's mission is to promote better stewardship of Wisconsin’s natural resources by advancing the understanding of invasive plants and encouraging the control of their spread. We continue to be involved with IPAW, which provides resources for planning, preventing, controlling, monitoring and educating people about invasive plants.
  • TNC is also a member of the Midwest Invasive Plant Network, which was formed in 2002 to reduce the impact of invasive plant species across the Midwest. The network does this through information sharing and by creating tools for invasive plant prevention, early detection, education, control and management. One of those tools is an Invasive Plant Control Database, which contains information on how to control many invasive plants common to the Midwestern United States.
  • TNC is working with multiple partners to tackle Asian carp, zebra mussels and other aquatic invasive species in the Great Lakes.
Underwater plant with a tangle of long stems and thin, feathery leaves.
Eurasian watermilfoil The invasive Eurasian watermilfoil causes serious damage to Wisconsin’s lakes and rivers, out-competing native plants that wildlife species depend on. © © Donald Hobern, Flickr CC BY 2.0


Everyone can be part of the fight against invasive species. Consider removing invasive species in your yard or adding native plants or non-invasive horticultural plants. You can report invasive species on the EddMaps app. When a problem species is reported, particularly an early detection species for the area, UW Extension and the WDNR can flag it and , when appropriate, help find a way to control and/or treat it. 

Volunteer with The Nature Conservancy

Wisconsin Volunteer Days
Volunteers pull invasive garlic mustard in Wisconsin.
Garlic Mustard Removal Volunteers pull invasive garlic mustard during a work day at Muehllehner Addition in Barneveld Prairie, Wisconsin. © Samantha Christian