Garlic mustard Alliaria petiolata

Garlic mustard

Description

  • Biennial herb in the mustard family
  • Leaves triangular to heart-shaped with scalloped edges.
  • Leaves emit distinct garlic odour when crushed
  • Clusters of white, 4-petal flowers usually occur at top of plants;
  • Flowering plants 5-150 cm tall
  • The fruits are black, cylindrical, and grooved.
  • The basal rosettes of garlic mustard looks similar to native wild ginger (Asarum caudatum) during the first year. Once it is in the second year of growth, the plant grows taller, produces flowers and seeds. It is then more noticeable and more distinguishable.
  • Thrives in moist, densely shaded areas to open, dry sites.

 

 

Management Options

  • Prevention: brush any seeds off your shoes, clothing, and any recreational equipment prior to leaving areas infested with garlic mustard. Be PlantWise and do not plant garlic mustard.
  • Hand pulling: smaller patches of garlic mustard can be hand-pulled. Best practice is to hand-pull prior to flower. The whole “s” shaped  root must be removed because new plants can sprout from root fragments. After hand pulling replace and pack down any disturbed soil and if possible replant/seed area with native species. Hand pulling must be repeated over serval years due to long lived seed bank (5-10 years). Bag all plant parts in a garbage bag to be disposed of properly at a landfill.
  • Cutting: second year plants should be cut at the base of the stem just after flower but prior to seed set. The plant will flower at different times of the year, therefore multiple treatments during the growing season are required. This is a preferred method because it reduces soil disturbance. Bag all plant parts in a garbage bag to be disposed of responsibly at a landfill.
  • Mowing: If the infestation is larger, regular mowing prior to flower can help control the population.
  • Clipping flower heads: Use with caution because clipping the flower heads encourages new flowers to emerge. Clipping flower heads can control the population if repeated on a regular basis throughout the growing season.
  • Chemical Control is available for garlic mustard. Herbicides must be applied in accordance with all label directions. Visit this website for more info.

 

Introduction and spread

  • Spreads by seeds hitchhiking on pet and wildlife fur, human clothing, machinery, in soil and water.
  • A single plant can produce up to 8000 seeds (10-20 seeds/pod).
  • Cut plants capable of re-sprouting from root crown and flowering <10cm tall.
  • Garlic mustard was originally found in Northeastern Europe. Early European settlers brought the herb over to use as a garlic flavored herb. It was also used for erosion control.

Consequences of invasion

  • Garlic Mustard is allelopathic; the chemicals produced in the roots have been shown to prevent the growth of other plants and grasses. Garlic mustard can displaces native forest species and decrease biodiversity.
  • Native butterflies commonly use native plants as their host plants, however they do use garlic mustard as a host plant, but garlic mustard leaves are toxic and their larvae die.
  • Garlic Mustard is a nuisance to dairy farmers, as cows grazing on Garlic Mustard may produce milk that is tainted with a garlic flavour.
Garlic Mustard is a threat to mature forests. Once introduced it can become the dominant plant in the forest understory in as little as 5-7 years! photo: Ryan Hodnett

Status in the CKISS region

  • Garlic mustard is currently listed as PREVENT for the CKISS region on the CKISS Priority List.
  • This means these species are not known in the region, but known from neighbouring areas, or are considered likely to arrive soon.
  • The species was recently discovered in Warfield (Spring 2021) and control efforts are planned to eradicate the population.
  • Report  ALL sightings of garlic mustard.

Additional resources