The Homeowners Column

The Homeowners Column

Waging war on weedy garlic mustard

Photo of Sandra Mason

Sandra Mason
State Master Gardener Coordinator
slmason@illinois.edu

Beaten, eaten, poked, smoked, scorned, but rarely mourned. At some time in our lives a weed will be on our hit list. However some weeds are more than just a "plant out of place".

Weeds at their worst can degrade natural areas and take over home landscapes to produce an unwanted one-plant show. Garlic mustard, Alliaria petiolata, has been the scourge of forested areas for years, but is now prevalent in gardens.

Garlic mustard is native to Europe where it hangs out in hedgerows, fencerows and open canopy woods. Here in the Midwest it loves the partial shade of our deciduous forests and backyard gardens where it can blanket the ground and smother other plants in its path.

As a cool season biennial, garlic mustard seeds germinate in early spring to form a rosette (bouquet) of kidney bean shaped leaves. In spring, usually starting the first of May, the mature plant sends up a 2.5-3 foot tall flower stalk with numerous small four-petaled white flowers. It's actually kind of pretty. This year with our warm March it started blooming in late March.

Plants set seed and the original plant dies; however, one plant can produce thousands of seeds. Just one year of seed production can produce a reoccurring nightmare of too much garlic.

The leaves of garlic mustard resemble violets, but garlic mustard leaves have more obvious veins and more deeply scalloped edges. Crushed leaves have a distinct smell of garlic except in late fall and winter.

Because of its ability to dominate relatively undisturbed forests garlic mustard is responsible for the decline of native plants and the insects and animals that rely on them. Not only does garlic mustard shade out other plants, but it also produces chemicals that can keep other plants from growing around it. It's definitely a bully biennial in the forest or the garden.

As with most exotic invasive weeds garlic mustard has no natural control here, even deer won't eat it. Research continues on biological control.

So what can you do to halt the spread of garlic mustard?

  • Don't dig wildflowers from the wild. This is wrong on many levels. Plus garlic mustard seeds and young plants can easily hitchhike on your illicit loot.
  • Always brush off any soil (that may contain seeds) from hiking boots and shoes after hiking in garlic mustard infested areas.

Control garlic mustard in your garden or woodland now. (Yes, right now.)

  • Hand pull plants. Be sure to get the entire root. Remove plants from area especially during flowering. Once the plant starts flowering, seeds can continue to develop on pulled plants. I have a "haz mat" compost pile where all my super weedy plants go for hyper vigilant eradication.
  • If removing plants by hand is too daunting right now at least clip off green seed stalks and ground level and remove from the site to help prevent continued buildup of seeds.
  • For large areas, weed whips can be used to destroy early flower stalks.
  • In lawn areas broadleaf weed herbicides used for dandelions can provide some control.
  • In fall or early spring it can be controlled by non-selective herbicide glyphosate sold in products such as Round up™ or Imitator™. Keep spray off desirable plants. Be sure to read and follow all label directions.
  • Prescribed fires in the hands of experts are important management tools in natural areas.

The key to garlic mustard management is early detection and eradication before plants flower. For pictures and information http://www.nps.gov/plants/alien/fact/pdf/alpe1.pdf

If you can't beat 'em, then eat 'em. Garlic mustard is reportedly high in Vitamins A and C. http://www.ma-eppc.org/weedrecipes.html

May is Invasive Species Awareness Month. Get involved in the Great Garlic Mustard Hunt. Visit http://web.extension.illinois.edu/cfiv/mn/3436.html for remaining dates and locations.

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