J. M. DiTomaso, University of California – Davis, Bugwood.org
Management Category
Squamish
Whistler
Pemberton
Vectors of Spread
Synonyms
Lawnweed, field burweed
ID Characteristics
Flowers: Are inconspicuous, small, yellow-green and disk-like. Their greenish flower heads grow in the basal rosette of the leaves.
Stems: Are hairy. Rosettes are 3 – 5 cm wide and 7 cm tall, with stems arranged in a sprawling pattern. Each plant has up to 10 stems growing from its base.
Leaves: Are alternate, slightly hairy, and feathery, similar to carrot or fern leaves.
Fruits: Are ovate and flattened, with a thick spine. Individual seeds are small (2.5 – 3.5 mm long) and shaped like a horn. They form groups of up to 10 sunflower-like seed heads.
Similar Species
Invasive
Wild carrot, also know as Queen Anne’s Lace (Daucus carota), grows in a similar habitat and has a similar leaf structure. Unlike carpet burweed, this plant’s stems can grow up to 1 meter tall.
Wild Carrot foliage (photo credit: Ohio State Weed Lab , The Ohio State University, Bugwood.org)
Pineapple weed (Matricaria discoidea) also grows in a similar habitat and has a similar leaf structure. Unlike carpet burweed, the larger flowers smell like pineapple when crushed.
Pineapple Weed. Credit: B. Klinkenberg.
Habitat and Origin
Carpet burweed is native to South America. It was first documented in Chile, in 1794. The first confirmed sighting in Canada was in Ruckle Park, on Salt Spring Island, BC, in 1996.
Carpet burweed grows best in open, grassy areas with disturbed, compact soils and full sunlight. Carpet burweed thrives in areas that are wet in winter, and dry and trampled in summer. It is commonly found in lawns, playing fields, and other disturbed, well-trodden areas.
How It Spreads
Carpet burweed is a winter annual, which means that it germinates in fall, lives through winter and dies in spring. Carpet burweed reproduces by seed. It produces 5-100 seeds per plant.
The bur-like seeds are well adapted for short-distance transport on the bottom of animal paws and hoofs, soft-soled shoes, and other soft materials such as tents and tires. Carpet burweed can also spread through the movement of contaminated soil.
Impacts
Ecological:
- Creates a dense, carpet-like groundcover that prevents the growth of native species.
- Reduces biodiversity.
Economic:
- Out-competes tended grasses and leaves behind wide, brown patches which are unsightly.
Health:
- The spiny seeds are painful for animals and humans to walk on.
Stop the Spread
Carpet burweed is not yet found in the Sea to Sky region, but is found in neighbouring areas and may arrive here soon. The goal is to prevent carpet burweeed’s introduction by focusing on education and awareness. If prevention fails, the goal will become immediate eradication following the proposed SSISC EDRR protocol.
Learn to identify carpet burweed: use the images presented in this profile page to learn how to identify carpet burweed.
What to do if you spot it: You can report any carpet burweed sightings by clicking here.
DO:
- Regularly monitor properties for weed infestations.
- Minimize soil disturbances and promptly revegetate disturbed areas to prevent the growth of carpet burweed.
- Ensure all flowering heads or buds are bagged or covered to prevent spread during transport to designated disposal sites.
DO NOT:
- Unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
- Plant Blueweed in a garden, no matter how well-contained its enclosure may seem.
- Compost any flowering heads or buds. Instead, dispose of carpet burweed in the general/household waste stream at the landfill as the seeds may persist the composting process.
- Move soil, gravel, or fill that has been contaminated with carpet burweed.
Control
Mechanical
- Small infestations of carpet burweed may be effectively controlled by hand-pulling, but this must be done before the seeds set.
- Ensure that any flowering heads or buds are bagged to prevent unwanted spread.
- For large infestations, flaming has been found to be the most effective method of removal, though it is often impractical.
- Mowing is ineffective due to the low-lying nature of the plant.
Chemical
- Herbicides such as clopyralid, picloram and triclopyr can be effective in removing this weed, however resistance has been reported. Moreover, picloram is not suitable for wet, coastal soils.
- Successive chemical treatments using alternating, selective classes of herbicides is recommended.
We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species specific treatment recommendations, and site-specific goals and objectives.
Cultural
Maintaining healthy, well-fertilized turf areas can prevent the establishment of carpet burweed.
Biological
There is no biocontrol available for this plant.
B.C. Distribution
Carpet Burweed Factsheet
Having trouble viewing the factsheet? Don’t worry, all the information is included on this page. You can also contact us with any questions.
References
- BC Parks and Invasive Species Council of BC, Best Management Practices for Invasive Plants in Parks and Protected Areas of British Columbia (2018 edition)
- Capital Regional District, Carpet Burweed Invasive Species Alert Sheet
- Center for Agriculture and Bioscience International (CABI), Soliva sessilis datasheet
- Coastal Invasive Species Committee, Carpet Burweed
- Electronic Atlas of the Flora of British Columbia, Soliva sessilis
- Fraser Valley Invasive Species Society, Carpet Burweed
- Gary Oak Ecosystem Recovery Team (GOERT), Soliva sessilis (Carpet Burweed) factsheet