Coastal Invasive Species Committee


Hoary Cress

Cardaria draba





 Family:  Brassicaceae

Origin:  Eurasia

Habitat:  Disturbed open sites: ditches, roadsides, riparian and wetland areas, pastures, orchards, vineyards.  

Distribution:  Kootenays, Cariboo; less frequent in Southern BC.

Legal Status: Noxious Weed (Weed Control Act)

Impacts:  Hoary Cress is the most common and aggressive of the three species of Cress (Whitetop, lens-podded, and hairy whitetop).  Once established, it can completely displace desirable vegetation by forming dense monocultures, and is very difficult to control.

Description:  Hoary Cress is an erect perrenial reaching a height of 2'.  The stems are generally straight and are covered with short hairs, and the leaves are alternate and grey-green in shape.  The inflorescences appear in spring to summer and have numerous small, white fragrant flowers.  The flowers have petals that are between 2 and 4 mm.  Hoary Cress reproduces primarily vegetatively, developing new shoots from their extensive root systems.  Depths of over 10' have been documented in some root systems.  

Management Strategy:  Hand-pulling is impractical due to its extensive root systems.  Mowing alone will not control Hoary Cress, however a combination of mowing and competitive cropping has been used to control other Cress species and may work for Hoary Cress.  Sheep and Goats will eat Hoary Cress, especially the seedlings.  Burning is not an effective control method again due to their extensive root system.  There are no biological control agents available for Hoary Cress.  2,4-D and Glyphosphate have been proven to be effective for controlling Hoary Cress.