Now is the Time to Pull Garlic Mustard, One of Michigan’s Most Invasive Weeds

By Rebecca Finneran

Michigan State University Extension

With the record warm spring, garlic mustard – one of Michigan’s biggest threats to our native woodlands – has reared its head and is quickly going to seed. Defenders of native habitat know only too well what this can mean for the forest floor – a rapid decrease in plants and animals alike. Since garlic mustard plants are so far along at this point, hand pulling seems to be the only option.

Background

Garlic mustard is a biennial, meaning it completes its lifecycle in just two years. The first year it is a diminutive, even attractive little plant with clusters of three to four rounded- to kidney-shaped leaves with scalloped edges. At first glance, it may be mistaken for a wild violet. These first-year plants remain green throughout the summer season and into the winter, making it easy to check for invasion throughout the year.

Early the next spring, robustly growing garlic mustard plants send up a 20 to 40-inch bloom stalk bearing tiny, white flower clusters. Leaves at this point tend to lose their scalloped edges, giving way to a more “toothed” appearance. Flowers pollinate quickly and become viable seeds within a few days after flowering begins.

Seeds mature and disperse as the slender seed capsules dry out and flip around in the wind. By the end of August, the plant actually disappears. At this time, unsuspecting gardeners and woodlot owners forget about garlic mustard, thinking it has gone away until the thousands of seeds germinate and begin their aggressive march through the forest. Seeing a forest woodlot that has been completely taken over by garlic mustard is a strikingly disturbing scene.

Pull ‘em out!

Even though hand pulling may be the best option at this point, other control measures can work when used at the right time. Any control method selected must be repeated for several years until residual seed from previous year’s plants has germinated. To a gardener or landowner, this could be a long time.

The plants are relatively easy to pull, but they are brittle, so be sure you are lifting the entire plant out of the ground and not just breaking off the top. This year, most of the plants have already begun to flower and set seed, so be careful to take the entire plant and not drop any seed capsules as you remove them.

Plants should be bagged or burned (with permission) since research has shown that composting is not a consistently good option. A large percentage of garlic mustard seed can withstand the compost heating process and may not be destroyed.

For larger stands, mowing or cutting has not proven to be the best solution either. If you can cut the plants before the flower buds have opened, you may be able to avoid seed production, but will not eliminate germination of latent seeds on the ground. Herbicides can be used in the early spring or again in late fall when native vegetation is dormant and will not absorb the product. The very nature of the forest floor is very delicate, so please read the label carefully before applying.

The forgotten green

A native to Europe, garlic mustard was brought to the United States as a valuable food source and its proclaimed medicinal properties. When settlers adopted other greens as their table favorites, garlic mustard was soon forgotten, giving the plant an opportunity to become an out-of-control weed.

The plants have a faint garlic smell and taste to the leaves, spurring many recipes to be generated for its use. Nutrient-rich leaves are dark green and said to add new life to salads and other dishes. So much interest has been generated over garlic mustard that culinary specialists around the country have tried to replicate uses for this forgotten green with modern recipes. A book titled From Pest to Pesto can be obtained from the Kalamazoo Nature Center that capitalizes on its uses. (If it becomes a popular vegetable, maybe this is the best way to get rid of it!)

Find out about other educational resources and classes at www.migarden.msu.edu and at Finneran’s blog. You can contact the MSU Master Gardener Lawn and Garden Hotline at 888-678-3464 with your questions.