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June 1, 2011

Key is early and frequent monitoring

PRESQUE ISLE, Wis. -- Located on Wisconsin's border with the Upper Peninsula of Michigan in Vilas County, this "almost an island" town's name even sounds like an idyllic vacation spot.

But if not for the sharp eyes and determination of a few local residents, the area would have quickly lost some of its Northwoods charm as it became infested with garlic mustard, an exotic, invasive plant that has become all too well known in much of southern Wisconsin.

The rapidly growing plant with small white flowers and a strong garlic odor has infested woodlots around the state. Once garlic mustard gains a foothold, it spreads rapidly and crowds out native wildflowers and tree seedlings.

garlic mustard pull
DNR forest ecologist Colleen Matula (left) with a group of Sierra Club volunteers and the bags of garlic mustard they pulled near Presque Isle.
WDNR Photo

"Fortunately, extensive public education efforts are helping residents of Presque Isle and other northern communities to spot new populations of garlic mustard," says Colleen Matula, a forest ecologist and silviculturist with the Department of Natural Resources.

Matula says that for the last four to five years, local resident Merrill Horswill has recruited friends and neighbors to pull every garlic mustard plant in and near Presque Isle.

With help from volunteers and Lee Shambeau, a contractor that specializes in invasive plant control, they now have the population down to a small enough number that a few volunteers can hand pull the plants that start to flower each spring.

"Working with volunteers and neighbors is key," says Horswill. "I enjoyed working with such a dedicated group. We will need to monitor it every year for at least the next 10 years, but as long as we don't let any plants go to seed we will be able to eliminate garlic mustard from the area."

Farther west, in the Flambeau State Forest, another new population was spotted early at a campsite and in a remote location, thanks to regular monitoring by DNR staff. After a few years of pulling flowering plants, this garlic mustard no longer even survives its first year to overwinter as a green rosette.

DNR staff use a propane torch to kill the newly emerged seedlings. This technique allows land managers to kill young plants without using herbicides.

"We try to educate local staff on why this is so important to control and they all take part in helping out," Matula says.

For those landowners in the southern part of the state, Kelly Kearns, a DNR native plant specialist, says there is no need to despair.

"If you have property that does not currently have garlic mustard, you can easily keep it out. Learn to identify it in all life stages and monitor for it regularly, Kearns says. "If the patch is small enough, pull every plant larger than a seedling. Larger patches require more hand pulling or a combination of pulling, targeted herbicide use and/or torching."

Kearns cautions that plants pulled during flowering can continue to develop seedpods, especially if they are stacked in piles where the plants stay moist and continue to grow even once they are out of the ground. Any plants with flowers or seedpods should be disposed of carefully. Drying the plants out and burning them where appropriate as well as burying works for those with larger properties.

City dwellers and others may need to send these plants to the landfill. As of 2010, a new state law allows plants legally listed as "invasive" to be sent to the landfill. Plants should be bagged and labeled "invasive plants - approved by DNR for landfilling."

"All sites that have been infested with garlic mustard require regular monitoring, several times a year to locate new patches that have emerged wherever a deer, squirrel or hiker inadvertently dropped a seed," Kearns says.

More information about controlling garlic mustard and other invasive plants is available on the invasive species pages of the DNR website.

FOR MORE INFORMATION CONTACT: Colleen Matula - 715-274-6321 or Kelly Kearns - 608-267-5066

Last Revised: Wednesday, June 01, 2011

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