Ann Cool, staff writer, Randall & Associates Publishing, LLC

Depending on where you live the garlic mustard plant can be a pesky weed or a healthful herb.

On this continent, garlic mustard (Alliaria petiolata), a member of the mustard family, is a weed that destroys neighborhood gardens, and threatens trailways and forests. In Europe, Asia and northwestern Africa, it is an herb that has culinary and medicinal uses.

The plant is known by a variety of names–Jack-by-the-hedge, garlic root, hedge garlic, sauce-alone, Jack-in-the-bush, penny hedge and poor man’s mustard. Ever since it was introduced by settlers to the U.S. in the 1860s, it has grown rampant and destroyed the biodiversity of our highways, byways and everything in between.

It is out of control for two reasons–insects and fungi that feed on it in its native source are not present in North America; and it produces thousands of seeds that spread rapidly. The Michigan Invasive Plant Council identifies the plantâ??s invasiveness rank as “consistently high across natural and managed systems with regional importance varying between medium and high in the Upper and Lower Peninsula ecological regions.â? This is due to its high seed reproduction and dispersal.

Garlic mustard is an herbaceous biennial–meaning it takes two years for it to complete its lifecycle. In its infancy, its leaves are heart-shaped and coarsely toothed. The young plant has green leaves in the shape of a rose that cover the ground. These leaves remain green through winter.  Garlic mustard flowers the following spring.  Second-year plants look entirely different. They are 2- to 3 1/2-feet tall with clusters of tiny white flowers of four petals each. They grow quickly into tall straight pods that become shiny and black. The seed is viable soon after the flowering stage.

According to Michigan State University Extension, garlic mustard as is â??one of the most potentially harmful and difficult to controlâ? invasive plants found in woodland habitats in North America and warns that â??dense stands of garlic mustard in the spring threaten showy spring blooming ephemerals [short-lived plants] like spring beauty, trilliums and trout lilies.â?

It is best to prevent garlic mustard plants from becoming established because even one plant can populate an entire site.  Therefore, it is imperative to eradicate it in the first year of growth. If you continue to see first year plants–the low growing ones–that means seeds have successfully reached the ground. If not discovered until early the next year, immediately eradicate them. As soon as the seed forms, it is immediately viable.

Although no method provides 100 percent control, some techniques are effective in removing garlic mustard:

1. Pull out or dig up the first year plant or plants from the entire area. They are easily pulled and bagged.
2. In smaller populations early in their development, you can cut the flower stalks, and collect the seeds in a plastic bag and dispose of them immediately.
3. Spray herbicide (glyphosate, the active ingredient in Roundup� and Rodeo�and triclopyr, the active ingredient in Brush-BGone � and Garlon�), often recommended by many extension services such as the University of New Hampshire.  Be sure to follow label directions when using any type of herbicide.
4. For large areas, burn with a controlled fire (be sure to acquire the proper permits).  Controlled burning in large natural areas must be monitored and repeated.

For more information on garlic mustard and controlling invasive plants:

http://invasiveplantsmi.org/
http://www.ipm.msu.edu/garlicmustard.htm
http://www.nps.gov/plants/alien/fact/alpe1.htm
http://tncweeds.ucdavis.edu/esadocs/allipeti.html
http://extension.unh.edu/resources/files/Resource000988_Rep1135.pdf