The Homeowners Column

The Homeowners Column

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Waging war on weedy garlic mustard

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Sandra Mason
Extension Educator, Horticulture
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 now has moved into 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 literally blanket the ground and choke out 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. Plants set seed and the original plant dies. 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, however, garlic mustard leaves have more obvious veins and more deeply scalloped edges. The crushed leaves also have a distinct smell of garlic except in late fall and winter.

Because of its ability to dominate relatively undisturbed forests it has lead to the decline of populations 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 finding a 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 wash off any seed hitchhikers from hiking boots and shoes if you have been in an area infested with garlic mustard. An especially good habit if you frequent any natural areas.

Control garlic mustard in your garden or woodland now before it sets seed.

  • Hand pull plants. Be sure to get the entire root or it may resprout. Remove plants from site especially in spring when they start to flower. Once the plant starts flowering seeds can continue to develop on pulled plants.
  • Garlic mustard can also be controlled in fall or early spring by the non-selective herbicide glyphosate sold in products such as Round up™. Keep spray off desirable plants. Be sure to read and follow all label directions.
  • In lawn areas broadleaf weed herbicide such as those used for dandelions can provide some control.
  • In natural areas prescribed fires may be used as a management tool in the hands of experts.
  • For extensive information about garlic mustard http://wiki.bugwood.org/Alliaria_petiolata

Early detection and eradication before plants set seed is the key to garlic mustard management. If you are not sure if what you have is garlic mustard, check out pictures at http://www.nps.gov/plants/alien/fact/pdf/alpe1.pdf . You are also welcome to send me pictures or bring a sample plant into our UI Extension office.

Garlic mustard pesto, anyone? Once popular as a food plant garlic mustard is reportedly high in Vitamin A and C. Here are some garlic mustard recipes provided as a service by the Mid-Atlantic Exotic Plant Pest Council http://www.ma-eppc.org/weedrecipes.html If you can't beat 'em, then eat 'em. bon appétit!

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