Weed Wednesdays are Back!

Did you know that the Alberta Weed Control Act recognizes two categories of invasive weed species? “Noxious” weeds are those species which property owners are required to control and prevent from spreading.

“Prohibited Noxious” weeds are those species which are required to be destroyed and eradicated from the landscape.

Throughout the summer, the Municipality’s Agriculture and Environmental Services Department will be highlighting an invasive plant species every week during the growing season. Stay tuned to learn more about weeds of concern and how you can do your part to control their spread.

Contact the Agriculture and Environmental Services department at 403-562-8833 for more information on invasive species in the Municipality of Crowsnest Pass.

Brush up on your weed identification skills using this online guide: ID Book 2012 PROHIBITED NOXIOUS (alberta.ca)

Hoary Cress

Lepidium chalepense (Lens-podded)
Provincial Designation: Noxious Weed

Description: Hoary Cress is a creeping perennial with deep rhizomatous roots, that can grow up to 9 meters. It can grow up to 60cm tall and has blue green to gray green colored leaves that are covered with soft white hairs. The leaves are lance to arrowhead shaped and occur in an alternate pattern. It has numerous white flowers with four petals borne on 1cm long stalk. Flowers cluster together at the top of the plant to create a flat-topped appearance. Above ground it reproduces by seed and can produce two crops of seeds per year. Hoary Cress requires disturbance to establish and can be found in meadows, roadside ditches, fields, waterways, cultivated lands and rangelands.

Significant facts: Hoary Cress can be toxic to cattle.

Control method: Encouraging healthy competition by maintaining stands of desirable vegetation. Mowing is effective but needs to be done repeatedly, especially early on before flowering and seed set occurs. There are products registered for use on Hoary Cress. Always read and follow label directions when using herbicides or contact a licensed contractor to perform the application.

Dalmatian Toadflax

Linaria dalmatica
Provincial Designation: Noxious Weed

Description: Dalmatian Toadflax has waxy, pale green to bluish green oval or heart-shaped leaves. It can grow up to 1.4 m tall, and the stalks have bright yellow flowers with a fuzzy orange spot on the lower lip. It has taproots and horizontal roots that can reach depths of 3 m. It grows well in dry sandy or gravely soils.

Significant facts: Dalmatian Toadflax is unpalatable or mildly toxic to livestock. It was introduced from Europe as an ornamental. Each plant can produce up to 500,000 seeds, viable for up to 10 years.

Control method: Remove upper plant prior to seed set to reduce seed production. Repeatedly hand pull young plants.

Dame's Rocket

Hesperis matronalis
Provincial Designation: Noxious

Plant Description: Dame’s rocket was first introduced as an ornamental and is also known as Dames Violet. It is a biennial, and a very prolific seed producer. It produces a rosette in the first year of growth and then a flowering bolt in its second year. Its flowers are very fragrant, with four petals arranged like a cross. Petals are generally purple but can also be white and lavender pink. Its leaves are alternate, and lance shaped with serrated edges. They are dark green in colour and hairy on both sides. Dame’s Rocket is often found growing as an escaped ornamental in moist habitats. It is often found in the moist, humus soils of wooded areas, and forest edges.

Significant Facts: Each plant can produce up to 20,000 seeds, making it a good invader in native plant communities. It can also be a host to crop diseases.

Control Methods: Hand pulling is the most effective method measure as the roots come out easily from moist soils. Plant density may increase the year following control work, but repeated removal will exhaust the seed bank.


Echium vulgare
Provincial designation: Noxious

Description: Blueweed is a short-lived biennial plant. In its first year of growth, it produces a low growing rosette, and a flowering bolt in its second year. It has a black taproot, and its stems can grow up to 90 cm tall. One plant can have one to several stems. Leaves at its base are narrow, lance-shaped, and are stalked. Stem leaves are alternate and become stalkless towards the stop of the plant. Both the stem and leaves are covered with stuff hairs. Flowers are 1-2 cm long and petals are bright blue and funnel shaped. Reproduction occurs through the dispersal of seeds. Blueweed is commonly found in gravelly riparian areas, roadsides, pastures, and meadows.

Significant Facts: Blueweed is toxic to horses and sheep.

Control Method: it is best controlled by hand pulling or digging when soil is moist. Mowing is effective but must be completed repeatedly. There are products registered for use on Blueweed. Always read and follow label directions when using herbicides or contact a licensed contractor to perform the application.