Burdock

Identification & Biology
Alias' : barbane, wild rhubarb
Latin Name : Arctium minus
Category : Terrestrial Plants
Description :
  • Biennial, reaching heights of 1-3 m tall
  • Flowers are purple, less than 2.5 cm across and borne in short-stalked clusters along the stems.
  • Mature flower heads form a prickly bur that sticks to clothing or animals to spread seeds
  • Leaf edges are toothed or wavy and the entire leaf is wholly underneath and dark green above
  • Large, fleshy taproot

Burdock reproduces only by seed, of which it can typically produce between 6000 – 16 000 per plant. Germination occurs mainly in the early spring and during the second year the plant produces a stout, grooved, rough stem with numerous branches. Flowering and seed production occurs from July to September, at which point seeds are mature and shed continuously throughout the autumn, winter, and following spring. It is able to spread very effectively by ‘hitchhicking’ a ride on animals and clothing. Its mature flower heads form prickly bur seed heads that readily stick to animal fur or clothing, and are then transported until the host manages to rid itself of it. This ‘hitchhiking’ is the primary mechanism for dispersal of common burdock.

Habitat

Burdock is established in coastal, central and southern BC. Major areas of concern in the province are the Okanagan, Thompson, Cariboo, and Peace Regions, though it is also present in the Kootenay, Mainland, and Vancouver Island areas. It grows in low- mid-elevations in grassland and forests and can commonly be found growing along roadsides, ditches, stream banks, pastures, and disturbed habitats.

Impact & Risks

Burdock is not considered a problem to crops since it is intolerant to cultivation. However, it does pose a problem to livestock as cattle are fond of burdock foliage but it causes a bitter taste to their milk if eaten in large quantities. This plant can also be a problem for sheep farming because the burs become entangled in their hair, damaging the quality of the wool. The burs consist of hundreds of tiny hooked slivers, and if these get into an animal’s eye they cause severe irritation. The burs can also affect sale price of animals if a producer is unable to remove them prior to putting them on the market. Burdock is also a concern for wildlife, particularly birds and bats that get tangled up in old burs.

Prevention & Mitigation

The most effective way to ensure that your lands do not become infested with burdock is by prevention. Here are some recommendations to prevent invasion on your property:

  • Don’t let burdock plants go to seed.
  • Regularly patrol your property for burdock plants, especially along creeks, lakeshores and other areas with moist soils, and immediately treat new infestations.
  • Cooperate with adjacent landowners and encourage them to control burdock • Re-vegetate disturbed, bare soils to a competitive perennial forage cover immediately after disturbance.
  • Clean burs from animals and from clothing and shoes before leaving infested areas.
Treatment & Disposal

Tillage can be used to eliminate the first year plants found in an area before they go to seed. First-year plants are difficult to control by above-ground cutting, as nutrient reserves of the taproot allow defoliated plants to survive. Mowing or cutting can also be used to eliminate seed production, but it must be done after the plant has bolted and before it has flowered to be effective and not spread seeds further. Dispose of burs caught on clothing or pets in bags in the garbage, or safely burn large cuttings. Chemical control is also an option. Before applying herbicides, read the label for full use and precautionary instructions. Consult the most recent edition of the Alberta Agriculture and Forestry Crop Production Guide for the selection and application of chemicals to protect your crop:

Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.