Overview
Mugwort (Artemisia vulgaris) is an invasive perennial frequently found in high elevation areas, disturbed habitats, meadows, valleys, and roadsides. Laboratory studies have found the presence of chemicals that could potentially suppress the growth of nearby plants.
Mugwort does well in partial to full sun and moderately dry to mid-moisture soils. It does not persist in wet soils, as it is susceptible to root rot. The plant
can reach between two and five feet in height. It is aggressive in its establishment and colonization on roadsides, right-of-way areas, and disturbed and uncultivated areas (Figure 1).
Common mugwort, native to Europe and Eastern Asia, is found throughout much of the Northeast, extending West to Minnesota and South to scattered areas in Florida. Many counties in Oregon and Washington states have also reported large populations. Mugwort was brought into North America as early as the 1600’s for medicinal purposes. It spread throughout the Northeastern U.S. as a contaminant on boats and ships and in nursery stock. The pollen is a common cause of allergies and hay fever, wherever abundant. The plant is a common ingredient in many products, including insect repellents.
Other characteristics of Artemisia vulgaris include:
- LEAVES: Alternate, papery, with large pinnate lobes. Green on upper surface, while undersides are covered with dense white to gray Foliage is aromatic, with a chrysanthemum or sage-like odor. Leaves emerging from ground have shallower and broader lobes, whereas leaves on mid and upper portion of the plant have lobes that are more linear and deeper.
- STEMS: Purplish-brown, branched, and covered with short
- FLOWERING: Inconspicuous blooms lack petals. They occur in small terminal clusters (at the tops of stems) and are yellowish, 2.5-3 mm long; composed of many disk flowers clustered onto a flat head.
- FRUIT: Single seed enclosed in a brown Oblong with a narrow base, with small bristles at the tip.
- REPRODUCTION/SPREAD: Spread primarily by aggressive rhizomes (horizontal underground stems), which form large, fast-spreading patches. Can also reproduce by seed. Some seeds will sprout when bare, disturbed ground is available to form new colonies.
Control
Mechanical Control:
- To prevent seed dispersal, mow from early summer to mid-September, before seedhead production or before seed has matured. The first two weeks of September are the best time to mow. Once cut, immature seeds will not mature into viable seed. Mowing after seed has matured, from mid-fall through winter, is not recommended, as it would disperse mature, viable seed. If mowing after the second week in September, collect, bag and dispose of mugwort cuttings, if possible.
- When possible, hand pulling very young plants in spring or early summer, before formation of rhizomes, may keep spread of populations in check and prevent establishment of new colonies. Scouting and prompt removal is
- A heavy-duty landscape fabric or other impenetrable mulch can be used to smother mugwort. This may require combining with other control methods to be successful.
- Since mugwort seeds sprout wherever there is exposed bare ground, stabilization and re-seeding of bare soil on roadsides with a grass cover will reduce help to curb establishment of mugwort populations.
Chemical Control:
Follow label direction when using all chemical treatments.
- Timing of any chemical control is critical. Follow label instructions. The dense hairs on the mugwort leaf make herbicide penetration difficult. A surfactant may be needed to allow the chemicals to take effect.
- Foliar spray of glyphosate applied in late summer or early fall will suppress mugwort the following year, but not necessarily eradicate it. More selective herbicides, such as triclopyr and clopyralid, effectively control mugwort.
- Consulting with or hiring a licensed pesticide applicator is recommended. Refer to CIPWG’s Invasive Plant Management Calendar