Noxious Weeds We Frequently Encounter

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Canada Thistle


  • 1-4' tall

  • Forms colonies and spreads vigorously via underground stems

  • Deep-rooted

  • Flowers are purple 1/2" - 1/3" wide – multiple flowers per plant

  • Aggressive and difficult to control

  • Tillage only increases numbers


Musk Thistle


  • 2-6' tall

  • Large deeply lobed spiny leaves

  • Large 1 ½" - 2 1/2 " wide purple flower

  • Invades pastures/rangeland forming dense stands

  • Very competitive


Dalmation Toadflax

  • 1-3' tall

  • Perennial, reproduces from roots and seeds

  • Leaves are waxy and wrap around stem, almost triangular or heart-shaped

  • Yellow  “snapdragon”- like flowers with a long spur

  • Aggressive weed with a deep root system

  • Difficult to control


Yellow Toadflax

  • 1-2' tall

  • Perennial, reproduces from roots and seeds

  • Leaves are numerous and narrow

  • Flowers are yellow, 1" long, look like a “snapdragon”

  • Aggressive invader with a deep root system

  • Difficult to control


Diffuse Knapweed

  • 1-2' tall

  • Stems rough to touch

  • Numerous narrow leaves

  • Flowers are white to purplish

  • Flowers July-September

  • Reproduces by seed

  • Highly competitive


Downy Brome aka Cheatgrass

  • Winter annual

  • Light green plant with soft hairs on the leaf

  • Germinates in late summer to fall

  • Mature plants dry out in summer months creating a fire hazzard

  • Seeds can embed in clothes and animal fur


Leafy Spurge

  • 1-3' tall

  • Reproduces by roots and seeds

  • Leaves are narrow, 1"-4" long

  • Flowers are yellowish green with similar color bract beneath

  • Very deep tap root system with large nutrient reserves

  • Exudes a milky sap that can irritate skin, humans and livestock

  • Seed capsules dry down and explode; can project seeds up to 15’

  • Very difficult to control


Common Mullein

  • 2-6' tall

  • Large fuzzy leaves

  • Rosette in the first year,  flowers in 2nd year

  • Flowers are yellow on long stalks

  • Stalks can produce thousands of seeds that persist in soil for years

  • Flowers and seeds June-August


Bachelor of Science in Landscape Horticulture with emphasis in Turfgrass Management from Colorado State University


- Weed Spraying

- Noxious Weed Consultation

- Pasture Management Consultation

- Soil Testing


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