Goutweed is a member of the carrot family (Apiaceae) and exhibits many of the family’s characteristics including an airy, white umbel of flowers appearing in early summer. Growing up to three and a half feet in height, the plant often appears in large, homogenous clumps as it gradually spreads outward via stolons. (4)
Leaves are divided, alternately arranged, and typically bear nine serrated leaflets. As with all members of the carrot family the leaves have a sheathing, clasping leaf base. The horticultural variety is variegated and has white margins on its leaves. (4)
Flowers are arranged in umbels born on long stalks and are approximately three to five inches in diameter. Seeds are very small, roughly oval in shape, and brown when ripe. (4)
Goutweed is a summer blooming perennial belonging to the carrot family. Capable of spreading rapidly via stolons, infestations of goutweed significantly alter the herbaceous layer, outcompeting native plants and decreasing plant diversity. (1) Furthermore, the highly shade tolerant goutweed may inhibit germination of tree and shrub seedlings in forested settings, thereby altering decomposition and nutrient cycling rates. (3)
No biological control option is currently available.
Manual or Mechanical Control
Pulling / Digging Up: Hand pulling or digging young plants is effective, if time consuming. Care must be taken to remove all rhizomes, otherwise, re-sprouting will occur. (3)
Mowing: Cutting at leaf out has been shown to decrease this species’ capacity for vegetative growth and spread. It is even more effective if performed repeatedly throughout the growing season in order to sap the plant’s starch reserves. Utmost care must be taken to complete control before the formation of fruit so as not to spread any viable seeds. (8)
Girdling: Not applicable
Prescribed Fire: No information available
Prescribed Grazing: Not a preferred species for grazers. (7)
Soil Tilling: Tilling is not a recommended method of control as goutweed often colonizes fragile, moist soils vulnerable to erosion and will re-sprout from root fragments. (7)
Mulching: Mulching can be a useful strategy in combination with other methods of management for small populations, such as hand pulling or cutting. (3)
Solarization: Not applicable
Hot Foam Spray: No information available
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. At times, the pest you seek to treat may not be on a pesticide label, requiring a 2ee exemption from NYSDEC. Always thoroughly read the label of any pesticide and consult the NYSDEC or a licensed pesticide applicator with questions.
Foliar Spray: A 2-10% solution of glyphosate will brown goutweed’s leaves but not kill the entire plant. Repeat application will be necessary in several weeks. Always read and follow all instructions on the herbicide label. (9)
Cut Stump: Not applicable
Basal Bark: Not applicable
Hack-And-Squirt: Not applicable
Stem Injection: Not applicable
Pre-Emergent Spray: No information available
General management overview and recommendation
Goutweed can be managed quickly and effectively by consistent, careful hand pulling if populations are discovered early. For large populations, repeated mowing (at least 3 times a season, at leaf out and before flowering onset) and repeat foliar spray of systemic herbicide such as glyphosate is the most effective management option.
Post treatment monitoring
Controlled populations should be revisited at least 2-3 times a season for at least 2-3 years to ensure exhaustion of the seed bank and that no re-sprouting has occurred.
Mowed, cut, or pulled goutweed can be composted so long no flower heads have gone to seed. All rhizomes should be disposed of in a landfill, or allowed to dry out completely, before composting in order to prevent regrowth.