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March 27, 2012

MADISON -- With the warm winter and the unseasonably warm spring, plants are emerging and growing several weeks earlier than usual, and this includes invasive plants that threaten to crowd out native species.

"Invasive plants don't pay attention to calendars, so if you are used to pulling your garlic mustard in April and May, you may need to adjust your plans this year," says Kelly Kearns, a native plant specialist with the Department of Natural Resources. "It is likely to be a banner year for weeds, so landowners and land managers need to get to work now to keep ahead of them."

Picture of Garlic Mustard
Garlic Mustard

Garlic mustard -- a biennial plant that smells like garlic and has four small white petals that flower in spring -- is famous for taking over entire forest floors and displacing trilliums and other wildflowers.

"Diligent efforts to prevent the plants from producing seed can keep woodlands free of the weed and protect the habitat for an array of wildflowers and native trees," Kearns says.

Small patches can be hand pulled starting as soon as the ground has thawed and the roots can easily be pulled out. But, Kearns adds, they must be pulled before seed pods mature, which is likely to be by mid-May this year.

If the bright green rosettes are pulled before they start to flower, the pulled plants can be scattered about in the woods. However, garlic mustard is so persistent that if flowering has begun and the plants are left in the woods or even in piles on a driveway, the plants will continue to grow and develop mature seeds.

"Pulled plants that have begun flowering need to be removed from the forest and buried, burned or sent to a landfill," Kearns says.

Although state law bans yard waste from landfills, any plants that are now regulated as "restricted invasive plants" can now be sent to landfills to keep their seeds and roots out of municipal and county compost facilities. The list of regulated invasive species and photos and fact sheets for most of the invasive plants can be found on the DNR's website and type in keyword "invasives."

Homeowners, and especially landowners, should be vigilant in watching for any plants that seem to be spreading and "taking over." Even some native species can become aggressive and more abundant than is desired. The key to keeping any invasive plants from completely overtaking an area is to keep them from reproducing.

Pulling, cutting, burning or using an herbicide before the plants flower to keep them from developing seeds is critical to keeping them under control. Some plants also spread by creeping stems or roots, so additional effort may be needed to stop their spread.

If herbicides are used, it must be done early and carefully to prevent killing wildflowers and other desirable plants. There is information about controlling these plants on the Web and in publications from the DNR and University of Wisconsin-Extension (exit DNR).

"Pay attention to what is growing on your land," Kearns says. "If something is increasing too fast, figure out what it is and what needs to be done to stop its' spread. We can all keep these invasive plants from spreading if we each take responsibility for our own little patch of the planet and don't let invasive plants from our land spread around."

Photos of garlic mustard can found on the DNR website.

FOR MORE INFORMATION CONTACT: Kelly Kearns, Invasive Plant Coordinator, Endangered Resources, 608-267-5066 or Paul Holtan, Office of Communication, 608-267-7517

Last Revised: Tuesday, March 27, 2012

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