Over the past three decades, alien invasive purple loosestrife has spread into many of Wisconsin's prime wetland habitats, shading out native wetland plants and habitat as it continues its prowl across the state. / Rob Zimmer/For Wisconsinoutdoorfun.com
Purple loosestrife was one of the first invasive plants to cause concern in Wisconsin decades ago when people realized that plants from Europe and Asia were causing irreparable damage to Wisconsinís native plant communities.
Purple loosestrife arrived in North America in the early 1800s, spreading to all 50 states. In the early 1900s, the plant was recorded in Wisconsin and it has spread to all 72 counties.
Decades later, the plant still poses a significant threat to the wetlands and marshlands of our state.
Like many alien invasive plants and animals ó those that are not native here but arrive from other continents by cargo ships or other means ó purple loosestrife threatens native plant communities due to its prolific nature and lack of natural predators in our state.
Its seeds are spread in many ways, and preventing the plant from going to seed is often key to stopping it in its tracks. The seeds are so tiny that they can be spread by wind, water, animals and even humans, who brush against the plant or come into contact with it, allowing the seeds to attach to clothing.
Once a new pioneer plant takes hold in a sunny wetland area, it can quickly produce a million seeds or more, and many more purple loosestrife plants, spreading quickly and shading out native wetland plants.
Native wetland plants, including water lilies, pickerel weed, arrowhead, and other important plants can be suffocated by the shade of a purple loosestrife colony. This, in turn, affects the many species of wildlife that depend upon the native plants, such as fish, snails, frogs ,toads, dragonflies and more.
Purple loosestrife was originally grown in gardens and ditches as an ornamental plant due to its striking and beautiful color. These plants can reach nine feet in height, making them formidable in the garden and even more threatening in the wild.
The long, vertical plumes of star-like, pinkish-purple flowers make it an attractive garden plant, but it is now restricted for sale and use in landscaping. While there are many similar species of loosestrife, some of them native to our area, purple loosestrife is not.
In recent years, success has been shown with special beetles known to feed heavily and exclusively on purple loosestrife foliage. These beetles are often raised by nature centers and other organizations as projects in specialized growing cages, then set free into infested areas where the beetles can defoliate the plants and slow its spread.
These beetles, also originally from Europe, were tested and brought in as a form of long-term biological control to the purple loosestrife problem.
Release of these special beetles in the state was first made in 1994, and over 10 years of monitoring has so far ensured that these insects do not attack native plants or croplands and pose no threat to humans.
Local purple loosestrife populations can be dramatically reduced by in the introduction of this beetle and programs have been implemented to allow property owners and organizations to raise and release these insects into infested areas.
Free equipment for this program is offered by the Wisconsin Department of Natural Resources.
Another way citizens can help slow the spread of purple loosestrife is to monitor their property and report invasions of the plant into new areas to the state DNR.
Visit the DNRís purple loosestrife mapping project at www.glifwc-maps.org.
Rob Zimmer:920-993-1000, ext. 7154, email@example.com