As you are driving through BC’s Okanagan, Cariboo, Boundary, Thompson and Kootenay areas, you may notice a small white flower sprinkled along roadsides or spread across a field like sifted white power. This is hoary alyssum (Berteroa incana). Declared a noxious weed under the BC Weed Control Act, hoary alyssum is a plant that is believed to have invaded North America by contaminants of clover and alfalfa seed.This plant is found on dry conditions and creeps into meadows and pastures. Another favourite spot to thrive is disturbed, open areas. Hoary alyssum is commonly found rooted in the sandy soils of construction sites, slopes alongside train tracts, or dusty roadsides.
Hoary alyssum grows as tall as 1.1 m, proudly displaying its white flowers. The plant blooms from early spring to late fall. The plant’s slender taproot is buried deep and progresses upward to a stem which is showered with star shaped hairs. Hoary alyssum’s leaves are grey with a rough texture similar to sandpaper.
The weed’s seeds are dispersed by wildlife, birds, machinery, vehicles, and footwear. Seeds also spread by a plant’s valves in the seed pod or as a contaminate of hay. Hoary alyssum seeds have the potential to remain dormant for as long as nine years.
Property value decreases by the presence of hoary alyssum. In addition, while not affecting other livestock, the plant can be potentially damaging for horses. The weed is toxic to many horses and can inflict fever, limb edema, and lamintis. In severe situations, if hay containing between 30-70% hoary alyssum is consumed, it can be fatal.
Although hoary alyssum has no biological agents, both mechanical and chemical controls may be utilized to gain effective management of the plant. In order to prevent the spread of this weed you can take simple precautions such as avoiding storage and parking in contaminated locations as well as removing plant material from vehicles, clothing, and equipment before leaving the site.
To find out more, click here or phone 1-888-WEEDSBC to report sightings.