Contact(s): Kelly Kearns, 608-267-5066
April 18, 2017
MADISON - Early spring is the best time to check gardens, yards and woodlands for garlic mustard and take measures to control this rapidly spreading invasive plant, state invasive plant experts say.
"It's important to control garlic mustard in early spring before the plants flower," says Kelly Kearns, an invasive plant specialist with the Department of Natural Resources. "Preventing the introduction of seeds and regular scouting are the keys to keeping uninfested yards and woodlands free of garlic mustard or other invasive plants."
Garlic mustard (Alliaria petiolata) can alter the composition of forests. Once introduced, it spreads and can dominate the forest floor, displacing native wildflowers, tree seedlings, and the wildlife that depend on them. Even mature trees can be impacted as chemicals produced by garlic mustard kills the beneficial fungi that tree roots need to absorb nutrients, Kearns says.
Garlic mustard is easily identifiable in spring. As a biennial, garlic mustard it takes two years to produce seeds. Seeds from previous year's plants germinate and can carpet the area. Seedlings grow rapidly and live through the winter as a low green rosette. When the weather warms, seedlings send up flowering stalks bearing many small four-petaled white flowers that develop into long thin seed pods.
"Anyone uncertain about the identification can crush the rapidly growing leaves and If it smells like garlic, you probably found garlic mustard," Kearns says.
To avoid introducing garlic mustard to a site, it's important to always clean boots, tools and muddy dogs after being in areas infested with garlic mustard, Kearns says. "Taking a few minutes to take these steps every time you leave an infested site can help save you literally years of work.
People who find garlic mustard on their property will want to assess the size of area covered by garlic mustard and the resources they have available, to help determine control methods.
Smaller populations can be contained by hand-pulling all second year plants. Any plants already flowering when pulled need to be removed from the site and carefully disposed of by bagging it and sending it to a landfill. Regulated invasive species are exempt from the rule that bans yard waste in landfills. Herbicides are generally used when sites are too large to hand pull. This can be combined with hand pulling the smaller patches, and with returning to the site to hand-pull or re-spray plants that were not killed initially. Fire, either with a propane torch, or as a controlled burn done by trained personnel, may be useful at some sites, Kearns says.
Regardless of the control method, Kearns cautions that property owners will need to continue their control efforts every year. "Seed is likely to stay viable for 10 or more years, which again highlights the need to control plants before they flower," Kearns says. Eradicating the patch requires a long term commitment. Forested sites without garlic mustard should be inspected for new infestations several times a year. Even in the northern part of the state, infestations are now being found.
In addition to garlic mustard there are a number of other plants that can invade forests and spread quickly. Homeowners, and landowners, are encouraged to be vigilant in watching for any plants that seem to be taking over.
For more information on garlic mustard and other invasive plants, search the DNR website, dnr.wi.gov, for keyword "invasive." Informational brochures may also be available at local University of Wisconsin Extension offices or DNR Service Centers.