Description: Hoary alyssum has a slender taproot and small white flowers in short spike inflorescences.
Type: biennial or short-lived perennial forb.
Habitat and Impacts: Hoary alyssum is found primarily on disturbed sites and prefers sandy or gravely well-drained sites. Hoary alyssum can be a serious problem for horse owners as ingestion of sufficient quantities can cause a number of diseases in horses. This species can also become a serious problem on heavily used rangelands and may displace native vegetation, reducing forage production for wildlife and livestock.
Method of Spread: This species reproduces exclusively by seed which is produced in moderate amounts by each plant. Seeds are produced from the first flower in late spring right up until frost and are spread by wind and water.
Location: A number of sites are scattered throughout the Cariboo Chilcotin Coast region and all are small and localized. Sites currently exist at Alexis Creek, within the city of Quesnel and Williams Lake, and along Hwy 97 near Lac la Hache and 100 Mile House. Recent inventory has indicated that this plant is expanding throughout the Cariboo. Hoary alyssum is very prevalent and beyond control in the Barriere area within the Thompson Nicola Regional District to the east of our border.
Mechanical: Hand-pulling can effectively remove small infestations, or cutting prior to seed set can control seed production.
Chemical: 2,4-D Amine, dicamba and mecoprop are effective at controlling hoary alyssum. This species has been difficult to control chemically in other areas of the province, possibly due to timing of treatments.
Biological: There is no biocontrol agent available for control of hoary alyssum.
CCCIPC Priority & Treatment Strategy: Priority 1 (new invader) in all areas except the central coast where it is classed as N/A ( not ecologically suited to the area) Since hoary alyssum is still a relatively new invader in the area, elimination of all sites is the goal.
Local Level - hand-pulling small sites, herbicide for larger sites.
Landscape Level – hand pulling small sites, herbicide for larger sites.
Hoary Alyssum seed pods and stem
Hoary Alyssum flower.
Hoary Alyssum plant
Invasive species profile taken from the Cariboo Chilcotin Coast Invasive Plant Committee Invasive Plant Regional Strategic Plan
Page last modified: March 15, 2017 09:36:29 PDT