Terrestrial invasive species

Nature

Most of these invasive plant factsheets are created from the booklet Minnesota invasive non-native terrestrial plants, an identification guide for resource managers.

Check the additional resources and herbicides table for more information.


Garlic mustard (Alliaria petiolata)

Garlic mustard (Alliaria petiolata)

Description:

Appearance: Biennial herbaceous plant with weak single stems 12 - 36" high in its second and flowering year. Only plant of this height blooming white in wooded environments in May.

Leaves: Round, scallop-edged, dark green; first year, rosettes of 3 or 4 leaves; second year plants have alternate stem leaves. Leaves and stems smell like onion or garlic when crushed.

Flowers: White, small and numerous, with four separate petals. Each plant has one or two flowering stems on second year plants.

Seeds: Slender capsules 1-2 1⁄2" long, containing a single row of oblong black seeds. Seeds are viable in the soil for 5 years.

Roots: White, slender taproot, "S"-shaped at the top.

Ecological Threat:

  • Garlic mustard spreads into high quality woodlands upland and floodplain forests, not just into disturbed areas.
  • Invaded sites undergo a decline on native herbaceous cover within 10 years.
  • Garlic mustard alters habitat suitability for native insects and thereby birds and mammals.
  • This European exotic occurs now in 27 midwestern and northeastern states and in Canada.
  • Garlic mustard is a MDA Restricted noxious weed in Minnesota.

 

Control Methods:

Mechanical
Pulling in areas of light infestations

Flowering stem cutting at ground level

Prescribed burning if there is enough fuel to carry the flames

Chemical
Spot application of 2% glyphosate in early spring or late fall when native plants are dormant

Biological
Biological control insects are not available at this time.  Research is on-going for biological control of garlic mustard.  See the US Forest Service's Biology and Biological Control of Garlic Mustard This link leads to an external site.PDF icon handbook for more information.

 

Native Substitutes:

More information