GARLIC MUSTARD - AN INSIDIOUS WEED

Kalamazoo, Mich.- Garlic mustard is a serious threat to native plants, including some of our most beautiful wildflowers such as trillium, bloodroot, and Dutchman's breeches. Garlic Mustard aggressively monopolizes light, moisture, nutrients, soil, and space. It frequently occurs in moist, shaded soil and along roadsides and edges of woods, particularly in disturbed areas. The current range of garlic mustard is from eastern Canada, south to Virginia, and as far West as Nebraska.

Accurate identification is essential; the coarsely toothed leaves give off an odor of garlic when crushed. The plant, a cool-season herb in the mustard family, has a two-year life cycle. In the first year, the plants appear as a rosette of green leaves close to the ground. The leaves remain green through the winter, and in the second year develop into flowering plants that are 2-3.5 feet tall that produce button-like clusters of small, white flowers, each with four petals in the shape of a cross. In May, seeds are produced in erect, slender four-sided pods. By late June, the plants have died, but leave behind erect stalks of dry, pale brown seedpods that may hold viable seed through the summer.

A single plant can produce thousands of seeds that can scatter several yards from the parent plant. The seeds in the soil may be viable for five years or more. The goal is to prevent seed production until the stored seed is exhausted. For light infestations, hand removal of the plant is possible. Because new plants can sprout from root fragments, it is important to remove the plant with its entire root system by grasping the base of the plant firmly and tugging slowly until the main root loosens from the soil and the entire plant pulls out. This is most successful when the plants are small and the soil is moist.

For larger infestations of garlic mustard, flowering stems can be cut at ground level to prevent seed production. Once seedpods are present, the stalks can be clipped, bagged, and removed from the site to help prevent continued buildup of seed stores. This can be done through much of the summer.

For very heavy infestations, application of the systemic herbicide glyphosate (e.g. Roundup) is also effective. Of course extreme care must be taken not to get glyphosate on desirable plants, and the application must strictly follow the package recommendations.

Regardless of the control method employed, annual monitoring is necessary for a period of at least five years to ensure that seed stores of garlic mustard have been exhausted. Your property will be more beautiful in the future if you control this invasive weed now.

For further questions on garlic mustard and other horticultural issues, please call the Beth Clawson, Consumer Horticulture Educator at MSU Extension in Van Buren County, (269) 657-7745.

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