Hoary Cress

Description

Hoary cress is a rooted perennial belonging to the Mustard family. It was introduced into North America in the 1800s, 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 sixty centimetres tall.

Type

Perennial forb

Habitat & Impacts

Hoary cress can occur in a variety of soil conditions but it favours alkaline soils with moderate amounts of moisture. It tends to do well at low-mid elevations where it occurs in hayfields, 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 hand pulling, 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 & 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.