Class B Noxious Weed
- Pioneer species that rapidly colonizes disturbed areas.
- European coltsfoot can quickly invade riparian areas after a flood and displace native plant communities, inhibiting the establishment of dominant tree species important for salmon habitat.
- Rhizomatous perennial; during winter the leaves die back and all that is visible at the soil surface is a cluster of flower buds.
- In early spring, flower stems elongate and flowers open, each with a single yellow flower head, resembling a dandelion.
- After flowers form, basal leaves on long petioles grow from the rhizomes, with green mostly hairless topside and white woolly undersides.
- Leaf blades are 2 to 12 inches long, heart-shaped to orbicular with angled small-toothed edges. Resemble a colt’s footprint.
- Often found in nutrient poor sites where anthropogenic or natural disturbance has removed vegetation. In riparian areas it is found in areas previously treated for knotweed.
- Grows in open to shaded disturbed habitats, forming extensive colonies. Plant populations are most abundant where the canopy is more open allowing for greater light transmission.
- Favors moist to wet soils but can also survive in drier conditions.
- Grows well on edges of rivers, lakes, ponds, wetlands, forests and other bottomland communities. Also, found in disturbed areas such as gravel pits, roadsides, and trails.
Reproduction and Spread
- Reproduces by seed as well as vegetatively through the fragmentation of rhizomes.
- A single flower head can produce an estimated 157 seeds that have numerous white hair-like bristles that help with wind dispersal.
- Seeds germinate soon after they are dispersed and do not remain viable in the soil for long; greatest viability up to 3 months after dispersal and are not viable after 5 months.
- Vegetative reproduction is favored on nutrient-poor sites. Fragments with just one node can survive and grow to produce new plants. Disturbance by water from eroding river banks can fragment rhizomes and spread clones to new locations.
- Early detection is key, as populations can be difficult to control once they are established.
- Small infestations can be carefully dug up, making sure to removal all rhizome fragments. Fragments left in soil will quickly re-sprout, so follow up treatments are necessary. Even with diligent removal efforts, eradication may not be possible.
- Cutting may eventually exhaust the root system. Cut flower heads before they bloom in the spring to stop seed production. Followed by repeated cuttings of above ground growth during the growing season. Leaves will quickly resprout from the rhizomes.
- Medium to large populations may require the use of herbicide. Apply to fully emerged leaves, application too early will result is decreased performance.
- The following herbicides have been shown to control European coltsfoot:
- Glyphosate (recommended) provides good control.
- Triclopyr and imazapyr had variable results. King County saw no reduction in large patches. However, smaller patches did show a reduction in size.
- Always replace the void and prevent future infestation, by replanting or seeding with native plant species.