Weeds Common to Flagstaff County

To ensure that the provincial Weed Control Act is enforced, which allows weeds to be identified and controlled in a timely, efficient and cost-effective manner, one hour free custom weed control is offered for the following noxious weeds: White Cockle, Scentless Chamomile, Absinthe Wormwood, and Toadflax. The only expense to the landowner is labour after the first hour and the cost of chemical.

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 spot treatments with Tordon 22K

For Leafy Spurge, Flagstaff County is currently combining chemical, biological, and grazing to help control spurge. Flagstaff County offers a program where a spray crew will come out for 50% labour costs and the full cost of chemicals.  

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 and glyphosate are both useful

 

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