Description:
Garlic mustard is considered an obligate biennial herb in North America (Cavers et al. 1979; Nuzzo 1991), although it is also described as a winter annual in other areas of its range. Garlic mustard seeds overwinter the first year, followed by germination and growth of the basal rosette early the following spring. These rosettes have stalked, reniform (kidney shaped) leaves. The leaves range from 2 to 8 inches long, and the leaf margins are coarse, round and irregularly toothed. The rosette overwinters, and the flowering stalk bolts early in the spring. The usually single stalk is sometimes slightly branched, and garlic mustard stands an erect 3 feet tall. The upper leaves are alternate, and their shape is deltoid (triangular), with the leaves gradually becoming narrower and smaller and sessile. At this time the basal rosette often withers. The overall plant is sparsely pubescent with simple hairs.

• Mechanical: Depending on the size of the infestation, hand pulling is an effective control for this short lived mustard. Mature plants are easily pulled. The rosettes tend to snap off at the root (personal observation). Another option is to cut the flowering stalk to only a few inches above the ground, just before the plant produces flowers. Remove these stems from the site. The site should be monitored for 2 to 5 years, until the seed bank is eliminated.
• Biological: The preliminary research for a potential biological control project of garlic mustard was initiated by Bernd Blossey in April 1998. A literature review reported 69 insects and 7 fungi as natural predators. 26 of those species were collected, 17 species were reared, and 6 species were selected as potential biocontrol agents: Ceutorhyitchus alliariae and C. roberti, shoot-mining weevils that attack rosettes and bolting plants; Ceutorhynchus constrictus larvae destroys seeds; Phyllotreta ochripes, a flea beetle larvae found mining the root and root crown; Ophiomyia alliariae a shoot-mining agromyzid; and a weevil, Ceutorhynchus scrobicollis (Hinz, H.L. and E. Gerber 1998).
• Herbicide: Herbicides are effective. Round-up® (glyphosate) at rates of 1%, 2% and 3% concentrations to rosettes in late fall or early spring reduced adult cover by 95% (Nuzzo). (These rates are from the Midwest.) Roundup and an amine formulation of 2,4-D can be applied in spring and fall. Basagram (bentazon) is highly effective for mid-summer control of first year rosettes growing in dense stands. No known chemical control for seedbank (Haber 1997). Please refer to herbicide labels for site specific control information. Refer to the State Noxious Weed Control Board site

For More Information:
Detailed information about Mustard Garlic is available at the Washington State Noxious Weed Control Board Web Site.