Invasive Species: Garlic Mustard

By Matt Forster

Every region of the world has its own ecology, one that represents a balance of power between thousands of species of plants, animals, and insects. As you can imagine, these are all very complex systems. For every plant that does what it can to find food and keep from being eaten, there is a bug trying to eat it and keep itself from being eaten. They each adapt and counter-adapt. The end result is that they find a way where all get a place at the table, so to speak, and none are nudged out. This hard-fought compromise can quickly fall apart, however, when a stranger comes to dinner.

Close-up of Garlic Mustard flowers.

Garlic mustard, or Alliaria petiolata to those in the know, is one of those strangers. A native of Europe, central Asia, and northwest Africa, garlic mustard was used throughout the region as an herb—one of the earliest known herbs, in fact. When crushed or cut, the plant gives off hints of garlic and mustard. Though the story of how the plant came to North American remains hidden in the fog of history, it’s usually assumed that Europeans settlers brought it with them. It’s easy to imagine that a clump of garlic mustard behind the homestead would be a welcome reminder of home and an easy way to dress up meals on the frontier.

The problem with garlic mustard comes when it makes its way into the wild. Suddenly this rather uninteresting plant is out-competing its neighbors for resources. Deer and other grazers have no interest in eating it, and the plant kills off its neighbors by producing allelochemicals. These are chemicals that affect the ability of the plants around them to grow. In the case of garlic mustard, the plant produces cyanide compounds that kill off the fungi which is necessary for the roots native plants absorb nutrients. Garlic mustard essentially makes the soil inhospitable to North American wildflowers, grasses, and even some trees. In its native Europe, it poses no such threat.

In Eastern North America garlic mustard has extended its reach into remote forests. Where people have difficulty removing the plant, it has become the dominant species under the canopy of trees. Here in the Midwest, however, garlic mustard is being fought regularly by an army of volunteers who head out every spring to local parks and green spaces to pull and bag as much garlic mustard as they can carry.

The trick is to pluck the plant in spring or early summer before it goes to seed in mid-summer. To that end there are annual competitions, like the Garlic Mustard Challenge, that are intended to help keep the Great Lakes Region free of this particular invasive species.

If you are interested in helping resist the tide of garlic mustard, most every conservation/preservation organization around has garlic pull events. The Michigan DNR, for example, has a list of garlic pulls scheduled for this spring. Nearby, the Bald Mountain State Recreation Area will host a garlic pull on Saturday, May 10, from 9 a.m. to noon. Follow-up pulls are also scheduled for Saturday, June 7 and Tuesday, June 10. Check the DNR Stewardship calendar for more details.