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Your Garlic Mustard Is Flowering, and Soon Will be Broadcasting Seeds. Now Is the Time to Pull It

May/June 2014

By Riverwoods Preservation Council

Each garlic mustard plant produces thousands of seeds. They are believed to be dispersed by the fur of animals, such as deer, horses and squirrels, and by people. The plant grows heartily in Riverwoods, and most vigorously in areas of trampled and disturbed soil. Seeds are produced within days of initial flowering. The seed pods open about a month later.

Hand pulling before or within a week or so after flowering is the most common method of control. The entire root must be removed. To prevent re-seeding, the pulled plants should be removed from the site.

Cutting the plant immediately after flowering, and before seeds develop, is effective if the plant is cut at the soil level. Cutting earlier or higher will prompt the plant to regrow. Cutting later will require removal of plants from the site to prevent re-seeding.

Chemical treatment (e.g., Roundup) is frequently ineffective. It also risks injuring or killing nearby vegetation.

Garlic mustard is a biennial, growing over a two-year period. In the first year, it is a low rosette. In the second year, it is a tall seed-producing flowering plant. Because seeds can be viable for 5 years, control of an infestation requires activity for several successive years.

Garlic mustard poses a severe threat to native plants and animals. It crowds out other plants, monopolizing moisture, nutrients and soil space, and reducing the food supply for native animals. Native animals do not eat garlic mustard, and butterflies are not attracted to it. In addition, garlic mustard is believed to contaminate the soil with chemicals exuded from its roots. The chemicals inhibit growth of other species.

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