Noxious and Prohibited Noxious Weeds Found Around the Crowsnest Pass

If you have any questions about the noxious and prohibited noxious weeds listed below and how to remove them, please contact the Agriculture and Environmental Services Department at 403-562-8600.

For weed and pest control, soil conservation and any agricultural or environmental concerns within the Municipality, please submit a form at https://crowsnest.omnigo.one/CESIReportExec/olr/main.aspx 

Common Tansy

Common Tansy (Tanacetum vulgare) is a perennial plant that was brought over as an ornamental from Europe. It is mildly toxic to humans and wildlife if consumed. You can identify these plants by their button-like yellow flowerheads that form dense clusters of 20-100 on the stem ends. Leaves have alternate arrangement; they are consistent in size and have deeply toothed margins giving it a fern-like appearance. These leaves will have a strong odour when crushed. Stems are often purplish-red, erect and woody. They can also be identified by their old woody skeletons from previous years. These plants prefer areas with full-sun and well-drained soil. You often see them roadside and along riparian areas. These plants can be upwards of 1.8 m tall and reproduce by seed and creeping roots. Common Tansy can produce up to 50,000 seeds which remain viable for up to 25 years. These plants can be controlled by cutting, mowing and herbicide application.

Creeping Bellflower

Creeping Bellflower (Campanula rapunculoides) is a creeping perennial that was introduced as an ornamental from Europe. You can identify these plants by their purple-blue, bell-shape flowers that have 5 fused petals, 5 green sepals and nodding flowers. The leaves are alternatively arranged and have a wide range in leaf variability but will generally be heart shaped with jagged edges. Often confused with the native Bluebells, the Creeping Bellflower is usually much taller, upwards of 100 cm, has larger flowers and creeping roots.  The Creeping Bellflower is a common lawn weed and is difficult to eradicate because it can reproduce by seed and aggressive thick creeping rhizomes. These plants can produce up to 15,000 seeds per plant! The best control methods include hand-pulling, digging, and smothering with tarps or cardboard.  

Yellow Toadflax

Yellow Toadflax (Linaria vulgaris) is a perennial, belongs to the Snapdragon family, native to Europe and is also known as butter-and-eggs! You can identify this plant by its yellow flowers that are attached by short stalks and the lower lip has an orange, fuzzy spot. The flowers are arranged in a dense cluster, or terminal raceme. The leaves are very narrow, alternate arrangement, pointed at each end and attached directly to the stem without clasping. These plants can tolerate a wide range of growing conditions and have an extensive creeping root system. They can also reproduce up to 5,000 seeds per plant! Repeated hand pulling is an easy control method for these woody, rhizomatous roots that may grow several meters long, herbicides work as well. Before this plant has flowered it is often confused with leafy spurge, however, this plant lacks the milky latex when broken apart!

Field Bindweed

Field Bindweed (Convolvulus arvensis) is also known as devil’s vine or wild morning glory. It is a perennial that is native to Africa, Asia and Europe. When it comes to reproduction, it can spread by seeds and creeping roots. The flowers are funnel shaped, white to pinkish in colour and about 2.5 cm in diameter. The flowers bloom in the summer and close when it is dark, raining or overcast. The leaves are dark green, arrowhead shaped and are alternately arranged on the vine-like stem. These plants have a deep taproot with extensive creeping roots that are whitish in colour, fleshy and brittle. This plant produces 500 seeds per plant and is viable for up to 60 years!  Field Bindweed prefers disturbed areas, pastures, cultivated fields and roadsides and are highly adaptive. Frequent hand pulling, cultivation or herbicides is best before seed set. This plant is problematic because it will host viruses that affect crops like tomatoes and potatoes and is mildly toxic to livestock. 

Oxeye Daisy

Oxeye Daisy (Leucanthemum vulgare) is a perennial that belongs to the Sunflower family and is native to Europe. You can spot these daisies by their yellow centered flowers that have 20-30 white petals located at the branch ends. The lower leaves are spoon-shaped and arranged alternately on the stems. The lower leaves are also lobed or have toothed edges and long leaf stalks whereas the upper leaves are narrow and clasped to the stem. The roots are short and fibrous making hand pulling an easy control method, but you want to make sure you dig the entire plant, removing the creeping, fibrous roots, and rhizomes to avoid regeneration. These plants tolerate a wide range of conditions and can be found almost anywhere. Buyer beware! This plant is often mixed into wildflower seed mixes! 

Common Mullein

Common Mullein (Verbascum thapsus) also known as Cowboy’s toilet paper due to its large, and very soft, felt-like leaves. This plant can be easily identified in its basal rosette stage or its erect flowering stem in the second stage of growth. The stems are woody and can grow up to 2.5 m tall, have a candle-stick appearance with 5-petaled, yellow flowers. This is a biennial plant in the Figwort/ Snapdragon family, native to Europe. This plant was used as a fish poison and brought over as a medicinal plant to treat an array of ailments but unfortunately has proven to displace native vegetation and overtake disturbed areas. Also, this plant is thought to serve as an alternate host for insects that negatively affect pears and apples.  

Common Mullein can produce up to 250,000 seeds per plant. The seeds generally don’t spread far from the plant but are viable for over 100 years making eradication difficult once established in an area. You can hand pull the entire plant but if there are flowers or seeds present you will want to bag and burn the flowered stems. The rosettes are easy to hand pull and can be controlled with herbicides.  

For large Common Mullein infestations, please contact the Agriculture and Environmental department to learn more about how to control this invasive weed! 

Common Burdock

Common Burdock (Arctium minus) was the inspiration for Velcro by George de Mestral in the 1940’s. It’s prickly seed heads spread by sticking to anyone or any animal that brushes up against it. These burrs may be great for inspiring Velcro but are an issue for small birds and bats when they become entangled. These burrs are not only difficult to deal with for small animals but also for horses and sheep when the burrs become trapped in their manes and de-value the sheep’s wool.  Common burdock has large leaves that can prevent sunlight and water to reach other plants, so you don’t typically get other plants growing near a burdock infestation. It is a biennial plant in the sunflower family, native to Eurasia and if often found in areas where the soil has not been disturbed. It prefers farmland, pastures, barnyards, fence rows, stream banks and forest open areas, edges, and understories.  

Often confused with Great Burdock and Wooly burdock, it can be differentiated by the size of the flowers and burrs, although, all three of these burdock species are regulated as noxious weeds in Alberta. Seed production begins in July and continues in the autumn spreading up to 16,000 seeds per plant.

You can treat this plant with herbicides, hand-pulling, digging, or cultivating prior to seed set. It tolerates a range of soil conditions and prefers full to partial sun.

Canada Thistle

Canada Thistle (Cirsium arvense) is a perennial plant that made its way to Canada through contaminated crop seed from Eurasia. It develops a rosette in its first year then reproduces through deep, spreading roots and by dispersing seeds that can remain viable for 21 years.  

This plant belongs to the Sunflower family and produces a purple- pink flower and has bracts with no spines. The leaves are glossy, alternately arranged, spine-tipped and stalkless with wavy edges. The stems are erect with prickly spines and can be slightly hairy. The Canada Thistle can grow up to 120 cm tall and is supported by creeping roots that can spread 4.5 m wide and 6 meters deep! This is the only thistle that has both male and female flowers.

You can find Canada Thistle just about anywhere in the province of Alberta. They are drought resistant and thrive in a variety of soil types in disturbed areas, crop and pasturelands, grasslands, stream banks and urban areas. This weed is problematic because it outcompetes vegetation causing severe crop-yield losses, reduces access and nesting cover for waterfowl.  Repeated cultivation, mowing, or hand-cutting reduces infestations and can eventually eliminate the plant.