Seasonal cycle: Seeds germinate in early April through May of
the first year. Plants produce only leaves during the first growing season. Garlic mustard
remains green throughout the year. In the second year, plants bolt and bloom from May
through early July, and produce fruit (siliques/capsules) in late July through August, The
plants die after producing seeds.
Distribution: Garlic mustard is native to Europe. In North
America, garlic mustard is widely distributed throughout the eastern U.S. and is found
from North Carolina to southern Ontario and Quebec. It is found as far west as North
Dakota, Kansas, Colorado and Utah.
Other points of interest: Garlic mustard was possibly brought
to North America by early settlers who used it as an edible and medicinal plant, although
no supporting evidence exists. The genus name Alliara refers to the distinctive odor of
garlic produced by leaves and stems when crushed. Garlic mustard poses a severe
threat to natural areas because of its ability to quickly dominate the ground layer to the
exclusion of native plants.
Control: Successful control methods include burning, pulling
by hand, and cutting flowering stems with a scythe or weed whip. Hand pulling, followed by
tamping disturbed soil, is recommended for light infestations. Control methods are most
effective before garlic mustard begins fruiting in late summer to prevent seed production.
If fruiting has begun, remove the viable seed from the area. Prescribed burning should be
conducted when at least two consecutive fires can be scheduled; burning only once may
increase the population of garlic mustard. The impact of the fires on the other plants in
the area must be considered. Chemical control, including the application of 1% Roundup'
(active ingredient is glyphosate), is most effective during spring and fall when other
herbaceous vegetation is dormant. Caution should be exercised when using chemical control
so that non-target species are not harmed. Garlic mustard spreads only by seed. Because
the seed bank is short-lived (two to five years), control methods should be continued for
a maximum period of five years to deplete the seed bank.
Additional information sources: Vegetation Management
Guideline, Garlic Mustard (Alliara petiolata (Bieb.J Cavra & Grande). V. Nuzzo, J.
Kennay, and G. Fell. Illinois Nature Preserves Commission, 1990.
Elemental Stewardship Abstract for Alliaria petiolata
(Alliaria opcinalis), Garlic Mustard. 1995. 1'. A. Nuzzo. The Nature Conservancy.
Unpublished document.
Gray's Manual of Botany. Eighth edition, corrected printing.
M. Fernald. D. Van Nostrand Company, New York, 1970.
Management and Control of Garlic Mustard. S. Greenlee. The
Nature Conservancy. Talk present d at Conference on "Managing Problem Exotic Plant
Species in Missouri and the Midwest," 1992.
Diagnostic information:
Flowers: numerous white flowers
(1/4" across) have 4 separate petals occurring at the top of the stem (in a terminal
raceme). Stigma simple and sessile. The petals and sepals fall off easily.
Leaves: basal
leaves are dark green and round-shaped with scalloped edges (2" to 4" across.
Stem leaves are alternate, sharply toothed, triangular or deltoid (1" to 3" long
and wide). Stems: usually a single (but 2 to 9 can be found) unbranched or few-branched
flower stalk (5" to 46" in height). Fruit: Siliques are 1" to 4-1/2"
long, narrow, linear, angled, four-sided, borne on short thick pedicels.
Root: White
slender taproot, with a crook or "s" shape at the top of the root.
This fact sheet has been prepared by The
Nature Conservancy
