What makes a plant a “weed” depends on your point of view. That’s not really the case with invasive species, though, that move into a territory, spread alarmingly fast and threaten entire ecosystems.

While most of us are aware of invasives endangering our Northwoods lakes, we have our share of terrestrial invasives, too, according to Ted Ritter, Vilas County Invasive Species Coordinator with the Land & Water Conservation Department. Together with Oneida County he has formed a new program, Wisconsin Headwaters Invasives Partnership (WHIP).

Right now, WHIP’s main focus is garlic mustard, an innocent looking little plant that invades woodland habitat and spreads quickly, displacing other plants in its wake. But Ted also has an eye out for Japanese knotweed, spotted knapweed, bush honeysuckles and buckthorn, among others.

He’s not alone in his concern, fortunately. WHIP has already enlisted the aid of such groups as The Nature Conservancy, township governments and the Lumberjack Resource Conservation and Development Council, a private nonprofit organization serving 10 counties in northeastern Wisconsin.

Together, they hope to combat invasives, but they don’t speak of eradication. “There’s no practical way to get rid of these species once they’ve taken hold,” explains Ted. “The best we can hope for is control. We target those species that we think it’s possible to slow down.”

Garlic mustard is the present target, mostly because of its visibility. “It stays green throughout the winter,” says Ted. “So as the other vegetation dies off in the fall, it’s easy to spot on the forest floor.”

It is to woodlands as Eurasian watermilfoil is to lakes, Ted explains.  Originally brought to the North American continent from Europe, where it grows as a harmless garden herb, garlic mustard has demonstrated its ability to reproduce and spread explosively.  Capable of adapting to a variety of soil types and sunlight conditions, it does well in the sandy, partially shaded woodlands of north central Wisconsin.

Garlic mustard releases a chemical substance into the soil that is believed to inhibit germination of trees and forest ground cover, Ted says.  This ability to “make its own bed” while also producing a high volume of seeds that can remain viable in the soil for many years is why garlic mustard is regarded as a major threat to woodlands.  

What WHIP plans to do starting this fall is to ask people to search public and private lands for garlic mustard. When a patch is reported, WHIP volunteers will visit the site and record the location with a hand-held Global Positioning System (GPS) device so that locations can be plotted on maps. Property owners can then be notified and a control plan established.

Control of invasives can be a complicated issue requiring different actions depending on the plant and its stage of life, the location, the season and weather conditions. Sometimes plants like garlic mustard can be effectively controlled by hand-pulling.

Other species, such as Japanese knotweed, require the use of herbicide to kill the root system. When applying herbicides, explains Ted, it’s important to get the right concentration of the proper chemical. Otherwise, you could destroy the top part of the plant while the root system remains intact. It just comes back again.

Ted sees WHIP as a potentially effective fighting force. “Right now, we can help with identification, general information and promoting awareness of the problem. Once we become what we want to be, we’ll have the partnerships in place, experts and personnel that can go in and help landowners to get rid of invasives on their property.”

Climate conditions have a big impact on the spread of invasives. Experts know that as temperatures rise, plants that usually are held back from “moving” up north because of the cold begin creeping toward us.

Drought conditions, such as those experienced here over the past few years, encourage some invasive plants. “The spotted knapweed is one that loves dry conditions and poor soil, so that has been spreading rapidly especially along roadsides,” says Ted. “If we were to experience wetter than normal conditions, spotted knapweed may not do so well.”

Any disturbance of the soil - housing and highway construction, logging operations, bridge building – can open the door to these species, which often produce huge quantities of seeds. Placement of topsoil and gravel, which can be full of viable invasive seeds, is another way they are spread.

One plant that seems especially dangerous is Japanese knotweed. “If you want to be kept up nights worrying, read about this,” says Ted holding a brochure. Growing in dense stands up to 10-feet tall, the plant crowds hillsides, streambanks and shorelines in impassable thickets.

Even hacking away at the thick, bamboo-like plants will not kill them, Ted says, and can actually make matters worse. “If the plant pieces are not properly disposed of and are allowed to enter a water body, they can embed in a bank where other clones can be established.”

But no one in WHIP wants to spell doom and gloom. “It’s a matter of education,” said Ted. “A large part of our success will be our ability to build awareness and bring people together to address the problem. If we can prioritize our limited resources we’ll be able to manage infestations.”

“People are the key. They already know how damaging water invasives can be. And while the lakes are important, so is the land. Invasive plants, if not controlled, can lower property values, impact forestry and affect tourism,” he says. “With enough awareness and a few good volunteers, we can get out there and control this problem.”

Anyone interested in joining the fight to search for and map garlic mustard is urged to call Ted at 715-479-3738 or email him at teritt@co.vilas.wi.us or contact Jean Hansen in Rhinelander at 715-369-7837 or jhansen@co.oneida.wi.us

More information on invasive species can be found at these websites:

WI DNR: http://dnr.wi.gov/invasives/fact/garlic.htm
Plant Conservation Alliance: http://www.nps.gov/plants/alien/fact/alpe1.htm
Wild Ones Natural Landscapers:  http://www.for-wild.org/download/garlicmustard.pdf