University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Garlic Mustard Invading Woodlands

May 10, 2001

Notice lots and lots of white flowered plants in and along wooded areas recently? This is garlic mustard, which has become a major weed problem in northern Illinois in the past few years that is choking out native plants. Garlic mustard prefers shade areas.

Garlic mustard is a native species to Europe that was introduced by early settlers. This plant is a biennial, meaning it has a two-year life cycle. The first year it is fairly low growing (around four to six inches) with rounded to kidney-shaped leaves, and does not flower. The second year, it gets taller (two to three feet) and the leaves may appear heart-shaped to more triangular with toothed edges. When the leaves are crushed, they have a distinct garlic smell.

The plant grows quickly in spring and produces clusters of small, four-petalled white flowers. Flowers develop into narrow seed capsules or pods. These capsules produce hundreds of seeds. Squirrels, deer, and humans walking through garlic mustard infested areas easily carry seeds. Garlic mustard spreads very rapidly.

Controlling garlic mustard requires more than a one-year effort. It may take two to five years of control efforts to reduce the seed bank. Hand pulling is probably the most effective method. Try to do this before the plant flowers and sets seeds. Garlic mustard starts very early in spring and also remains green into late fall, so learning what it looks like and where it has developed is helpful in planning future control efforts. Right now it is very visible while two-year plants are blooming.

Herbicides may be used for control. Glyphosate (Roundup, Kleeraway) is a nonselective herbicide that can carefully be used as a spot-treatment, but be aware that any green plants in the vicinity hit by the spray will also be affected. Consider late fall or very early spring application in the future when other plants may be dormant but the garlic mustard will be green.

 

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