Garlic Mustard (Alliaria petiole)
Keys to ID:
- Flowers are numerous, four-petaled, and white.
- Leaves have a distinct onion-like odor when crushed.
Identification:
- Lifecycle: Biennial
- Growth form: Forb
- Flower: Numerous white flowers with four petals in clusters atop flower stalk. April thru May.
- Seeds/Fruit: Fruits are slender capsules that produce a single row of black, oblong seeds with ridged seed coats. A single plant may produce hundreds of seed.
- Leaves: Lower leaves are rounded with scalloped edges and mound a mounded rosette Stem leaves are toothed, alternate, and more triangular (King County Noxious Weed Control Program 2010).
- Stems: Mature plant has erect stems growing 1 to 4 feet in height.
- Roots: thick taproot; roots produce allelopathic compounds that inhibit seed germination of other species.
- Propagation: Seeds viable in soil for up to five years.
Control:
Mech: Hand pull from April to June, after they begin to bolt, until they are through flowering, and while the seed pods are still green. Plants in flower or even in bud are able to form viable seeds even after they are pulled, therefore plant pieces must be carefully bagged and disposed of. In areas where mature plants are pulled, there are usually many small rosettes and seeds left in the soil. Carefully search the area for rosettes and dig them up with care as roots break off easily and re-sprout (King County Noxious Weed Control Program 2010).