Description: Hoary cress is a rooted perennial that belongs to the Mustard family. It was introduced into North America in the 1800’s, most likely in contaminated alfalfa seed (Kadrmas and Johnson, 2002). Hoary cress is also referred to as “white top” because of the numerous white flowers that are produced at the top of the plant (Ministry of Agriculture and Lands, 2002). Clasping, arrowhead shaped leaves are present along the stem. The leaves are covered with soft white hairs giving them a gray-green color. Hoary cress can grow up to 2 feet tall.
Type: Perennial forb
Habitat and Impacts: Hoary cress can occur in a variety of soil conditions but favour alkaline soils with moderate amounts of moisture. It tends to do well at low-mid elevations where is it occurs in hay fields, rangeland meadows and along roads and roadside right of ways (Ministry of Agriculture and Lands, 2002).
Method of Spread: Reproduces by roots and heart-shaped seeds. Each plant can produce 4,800 seeds that can remain viable for up to 3 years in the soil (Kadrmas and Johnson, 2002).
Location: Hoary cress is not well established in the Cariboo Chilcotin Coast region. Currently there is a single infestation located along the east side of Highway 97, just north of 103 Mile. There are no records of plants spreading from this site.
Mechanical: Mechanical treatments, particularly handpulling, are the less favourable as the entire root system must be removed. Leaving a single root fragment can result in the emergence of a new plant. Frequent mowing prior to seed production has proven effective in reducing seed production and plant vigour.
Chemical: Dicamba and 2, 4-D are effective herbicides that can be used to chemically control hoary cress during the early pre-bud stage. Glyphosate has shown effective control during the flowering stage. (Ministry of Agriculture, Lands and Fisheries, 2002)
Biological: There is no biological control agent available for Hoary cress in British Columbia.
CCCIPC Priority and Treatment Strategy: Priority 1 (new invader) for all areas except the Central Coast where it is classed as N/A (not ecologically suited to the area). Where hoary cress has been categorized as a new invader the current management goal is elimination via chemical treatment.
Local Level – frequently mowing small infestations.
Landscape Level - chemical control for larger sites.
Hoary Cress flower.
British Columbia Minstry of Agriculture and Lands
Hoary Cress plants.
Hoary Cress infestation
Invasive species profile taken from the Cariboo Chilcotin Coast Invasive Plant Committee Invasive Plant Regional Strategic Plan
Page last modified: October 30, 2018 09:44:02 PDT