Mugwort is a tall, herbaceous, perenniala plant whose growth dies down annually but whose roots or other underground parts survive plant growing 1-2 meters (rarely 2.5 meters) tall, with an extensive rhizome system. Rather than depending on seed dispersal, it spreads through vegetative expansion and the anthropogenicenvironmental change caused or influenced by people, either directly or indirectly dispersal of root rhizome fragments. The leaves are 5–20 cm long, dark green, pinnate, and sessilea leaf whose blade is attached directly to the stem, lacking a petiole, with dense, white, tomentosecovered with densely matted woolly hairs hairs on the underside. The erect stems are grooved and often have a red-purplish tinge. The rather small florets (5 mm long) are radially symmetrical with many yellow or dark red petals. The narrow and numerous capitula (flower heads), all fertile, spread out in racemose panicles. It flowers from midsummer to early autumn.
Mugwort commonly invades waste places such as old fields, roadsides, parking lots, forest edges and ditches. It is a very common plant growing on nitrogenous soils, such as waste places, roadsides and other weedy and uncultivated areas.
History and Introduction
Mugwort was introduced to the United States inadvertently, Mugwort was a likely stowaway in the ballast soils of ships visiting the then colonies.
Traditionally, it has been used as one of the flavoring and bittering agents of gruit ales, a type of unhopped, fermented grain beverage. In Vietnam, mugwort is used in cooking as an aromatic herb.
Mugwort was known for its success in repelling moths. It is highly sought after for its medicinal, culinary, and ceremonial uses.
Mugwort spreads aggressively via an extensive rhizome system and can form large stands that displace native species. It is considered a problematic weed of nurseries, orchards, sports fields, forest edges, and roadsides. Mugwort is wind-pollinated and therefore produces a lot of pollen that can be distributed over long distances, causing severe symptoms in allergic humans. Mugwort is difficult to eradicate because its rootstock overwinters in the ground and it has a large seed bank.
Mugwort primarily spreads locally via underground rhizomes, although sexual reproduction is possible. The species does produce plenty of viable seed each year and although these seeds lack a specific dispersal mechanism, they can be distributed via agricultural products, such as hay, small animals, wind, water, and soil, where they remain viable for three to four years. In the right conditions, a single plant can produce 200,000 seeds. Vectors for dispersal include wind, small animals, water, agriculture and human activity (such as hiking).
Sequential mowing coupled with sequential herbicide treatments will provide the highest rate of control. Plants should be mowed at least twice prior to foliar applications, and at least two applications will be necessary during the first year of control, ideally beginning in late spring. For very small infestations, cutting and spot spraying or careful hand pulling—making sure to extract as much of the rhizome as possible—will eventually achieve eradication.
Mugwort is highly tolerant of mowing, although at least three mowings per year for at least two years does decrease infestation size by approximately one fifth. For greatest effectiveness, mowing works best in conjunction with chemical control. If mowing is utilized as a management method it must be completed before fall seed set.
Tilling and pulling by hand is not advisable. It is an ineffective method of control. Tilling and hand pulling may fragment roots and encourage re-sprouting and vigorous growth.
The pesticide application rates and usage herein are recommendations based on research and interviews with land managers. When considering the use of pesticides, it is your responsibility to fully understand the laws, regulations and best practices required to apply pesticides in a responsible manner. Always thoroughly read the label of any pesticide.
Mugwort is tolerant to a variety of herbicides and generally requires repeat applications to achieve suppression or control. Higher rates of control (80%-90%) can be achieved with piclorama systemic herbicide used for general woody plant control and clopyralida selective herbicide used for control of broadleaf weeds, especially thistles and clovers as opposed to glyphosatea widely used herbicide that can kill certain weeds and grasses, it works by blocking an enzyme essential for plant growth, which needs higher concentration levels and at least two applications to achieve 70%-80% control. Always read and follow all instructions on the herbicide label.
Riverside Wormwood, Felon Herb, Chrysanthemum Weed, Wild Wormwood, Old Uncle Henry, Sailor’s Tobacco, Naughty Man, Old Man, St. John’s Plant, Maiden Wort
Temperate Europe, Asia, and North Africa
Carruth’s Wormwood (Artemisia carruthii)