Invasive Watch: Garlic Mustard
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Get information on identifying and controlling this noxious weed.
What to Look For
Garlic mustard is a cool-season biennial herb with basal rosettes of round to kidney-shaped green leaves the first year, becoming 2-4 feet tall the second year. The rosettes remain green through the winter and develop into mature flowering plants the following spring. Mature plant leaves alternate up the stem and are larger near the base. Leaves are triangular to heart-shaped, coarsely toothed and give off a garlic odor when crushed.
In early spring, white petal flowers grow in clusters at the end of the stems. From these, numerous seeds are produced in erect, slender pods and become shiny black when mature. These seeds may lay dormant for two to six years before germination. By late June, second-year garlic mustard plants will have flowered and died.
Where it is Found
Introduced from Europe into the United States in the 1800s for medicinal purposes and food, garlic mustard now frequently grows in dense patches along rights-of-way, ditch banks, forested areas under partial shade, shaded flood plains, edges of forests or trails, vacant lots, parks and natural areas. Disturbed areas are more susceptible to invasion. However, it is one of only a handful of non-native plants that has proven an ability to successfully invade healthy and intact forest understories, thereby greatly reducing the diversity of all species.
Once established, garlic mustard outcompetes native plants by monopolizing moisture, light, nutrients and soil space.
How to Treat It
For control of garlic mustard with selectivity to desirable plants, apply Garlon® 4 Ultra herbicide as a foliar spray at a rate of 1.25 to 2.5 percent. Apply to the targeted plants during the prebolting stages of growth when garlic mustard is green and susceptible. However, do not apply Garlon 4 Ultra when the temperature is below 40° F, plants are in drought stress or when rain is expected within one hour.
- For hydraulic spray applications: Use foliar rates as listed above. The addition of a surfactant is not necessary, but a nonionic surfactant can be added at 0.25 percent v/v.
- For backpack applications to foliage: To treat smaller infestations or to do follow-up spot treatments, the recommended spray mixture is 2 to 3 fluid ounces of Garlon 4 Ultra in 1 gallon of water.
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