Weeds Common to Flagstaff County

For White Cockle, Scentless Chamomile, Absinthe Wormwood and Toadflax, Flagstaff County offers a program in which a spray crew will come out and spray infested areas. Landowners are responsible for labour and chemical costs.

White Cockle
White cockle

Characteristics

  • Biennial
  • Separate male and female plants
  • White flowers open in full sun and close in evening
  • Hairy stems
  • Similar to Bladder Campion and Night Flowering Catch Fly

How it Grows

  • Emerges early in the spring
  • Taproot forms first followed by spreading lateral roots
  • New plants can start from root pieces
  • Grows in reduced tillage, forage crops, roadsides, waste areas
  • Female plants capable of producing 24,000 seeds

Prevention 

  • Know the source when purchasing hay and straw
  • Request a weed seed analysis certificate when purchasing forage seed
  • Prevent the plant setting seed by removing it through hand-picking
Scentless Chamomile (Mayweed)
scentless chamomile250

Characteristics

  • Plants can be summer annuals, winter annuals, or short-lived perennials
  • Has daisy-like flowers with raised yellow centers and white petals
  • Hairless stem has light green leaves that alternate around it
  • Leaves are very finely divided and smooth

How it Grows

  • May reach about 1 meter tall
  • Will flower in late June through to September
  • Will produce around 300,000 to 500,000 seeds per plant
  • Seeds will survive in soil for long periods of time (up to 20 years)

Prevention

  • Tarping loads of grain and bales
  • Mowing non-cropped areas about twice a year
    Hand pull, hoe, and till in small areas before it flowers
  • Harvest and till weedy areas separately, which helps keep weeds in confined area
    Shallow tillage on hot, dry days
  • Plant competitive crops such as barley or winter wheat
Absinthe (Wormwood)
absinthe250w

Characteristics

  • Perennial
  • Leaves are silvery-grey, alternate, lancolate, and undivided, sage-sage-like odor when crushed
  • Flowers are yellowish-green borne on a spike-like panicle
  • Fruit is numerous small, round seed.

How it Grows

  • Gradual deep tap root
  • Inhabits waste areas and pastures
  • Out competes forage plants

Prevention

  • Mechanical Control (tillage)
  • Chemical control through spot treatments
Toadflax
toadflax250w

Characteristics

  • Bright white and yellow flowers and resembles snapdragon flowers
  • Hairless stems are fully covered in numerous, hairless leaves
  • Bushy appearance is due to the new clumps of shoots along the side of the creeping roots

How it Grows

  • Will flower from June through to the fall
  • One stem produces up to 5,000 seeds
  • Seeds from Toadflax will germinate as soon as they spread and may remain in the soil for up to 3 years

Prevention

  • Constant cultivation will control it but will not prevent it
  • Mowing helps control but will not eliminate weed
  • Seed at a heavier rate than normal to prevent competition
  • Biological control with special species of beetle and weevil feed in the flower and prevent seed production
  • Chemical control through treatments with Grazon

Leafy Spurge is classified as a noxious weed under the Alberta Weed Control Act and therefore holds an obligation to be controlled. Some control methods include grazing, cultivation, mechanical, chemical, and biological control. In support of private landowners that are needing assistance to suppress the spread of Leafy Spurge, Flagstaff County has brought back the Leafy Spurge Program. Click HERE to find out more.

Leafy Spurge
leafy spurge 250w

Characteristics

  • Deep-rooted perennial
  • Can spread through re-vegetative re-growth of the roots
  • Small, yellowish green flowers found in clusters are enclosed in yellow-green brackets
  • Plant contains a milked white latex, which is toxic to some animals and can cause blistering and irritation on skin

How it Grows

  • Can grow to a height of 3 feet in the spring
  • Can be found growing almost anywhere, especially in sandy and marginal soils
  • Seeds occur in clusters of three; seed capsules will explode when dry

Prevention

  • Goats and sheep will readily graze this plant
  • Intensive cultivation throughout the growing season, or fall-only cultivation can reduce the presence
  • Mowing has proven somewhat effective mechanical methods against this plant
  • There are a few herbicides that have had success reducing the density of infestations when used at proper timing
  • Five types of flea-beetles and two types of moths are available for bio-control

For Common Tansy and Canada Thistle, Flagstaff County offers a program in which a spray crew will come out and spray infested areas. Landowners are responsible for labour and chemical costs.  

Common Tansy
commontansy250w

Characteristics

  • Very distinguishable by its strong fragrance, when leaflets are crushed
  • Bright yellow flowers are arranged in clusters and are flat-topped
  • Leaves resemble the leaves of a rose

How it Grows

  • Flower clusters can be as numerous as 200
  • Stems of tansy have been known to grow to 6 feet tall
  • Seeds are the primary source of reproduction, it can also spread through root stalks

Prevention

  • Tansy does not endure tillage
  • Mowing (dead heading) the flowers while they are still yellow will also help to control seed production
  • High seeding rates
  • Herbicide options are available through Flagstaff County
Canada Thistle
canadathistle250w

Characteristics

  • Most recognized characteristic of any thistle is the spiny, prickly leaves
  • Flower head is shaped like a vase
  • Bracts are spineless and appear purple, pink, or white in colour
  • Each flower has an odour, which attracts honeybees

How it Grows

  • Flowering occurs between mid-June and into September
  • Plants can reach heights of 1.2 to 1.5 meters tall
  • Extensive root system where vertical roots will grow downward to 7 meters in order to reach the water table
  • Plants can be produced from small pieces of root and shoots
  • Each of the flower heads could contain about 90 seeds, which means a plan could produce close to 5,200 seeds
  • Seeds can remain in the moist, loamy soils for up to 21 years

Prevention

  • Regular cultivation
  • Pulling or hand-cutting several times through the season
  • Late spring burns in May and June
  • Chemical control can also be used; 2-4D, products containing clopyralid or glyphosate are useful

Click HERE for more on provincially regulated weeds.