There are a number of invasive plant species in the Central Kootenay.
Download our most recent priority list here (PDF - 44KB)
For more detailed information on the biology, distribution, and management strategy for each species in our region, please see the Invasive Plant Profiles
Orange and Yellow Hawkweed
Orange hawkweed (Hieracium aurantiacum) is a beautiful flower that often appears in gardens. With a single stem with black hairs, and a rosette of leaves at the base of the plant, it is easy to identify. It is often introduced through "œwild seed mixes"� or by transplants from one garden to another.
Yellow hawkweeds are similar, but with yellow flowers. There are numerous types of yellow hawkweed including both native and non-native species.
Hawkweed spreads both by seeds and by under-surface lateral roots, making it difficult to control. A 1 m square patch of orange hawkweed can produce over 40,000 seeds per year! This species is related to yellow hawkweeds, some of which are also non-native invasive species such as mouse-ear hawkweed.
Because hawkweeds spread by stolons (vegetative shoots), mechanical methods of control are not very effective. It is possible to dig up rosette plants, being careful not to break the roots since new plants can re-grow from the remaining pieces. If flowers are already present, be careful to dispose of the plants carefully, by placing them in a plastic bag or similar container so seeds cannot spread. Regular mowing before the flowers go to seed can reduce seed production.
Light infestations of orange hawkweed can be reduced by fertilizing with ammonium sulphate (fertilizers marked with 24-00-11). Another method of killing off plants is to use solarization (cover with black plastic) followed by heavy doses of urea. Some people have also tried a vinegar recipe, using 1 gallon vinegar, 1 tsp salt, and 1 tsp dish soap to spray on the plants in the spring. Reseeding infested areas with native or non-invasive plants can help provide competition for hawkweed and encourage a healthy plant community.
Herbicides are one of the most effective control methods for hawkweed. For herbicide information please see this Weeds BC info sheet.
Orange hawkweed is found throughout the Central Kootenay in relatively low abundance. It is definitely on the increase with near monoculture densities appearing in Nelson, north shore, Kaslo and north.
Additional Information:
www.agf.gov.bc.ca/cropprot/hawkweed ...
Invasive Plant Profile:
Orange hawkweed - Hieracium aurantiacum - 802.1 KB
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