Nodding thistle (Carduus nutans)

Nodding thistle

(Carduus nutans)

Description

  • Solitary flowers at the end of a 20cm-2.5m tall stem
  • Alternate leaves, waxy cuticle
  • Flowers are purple-red, and at the base of the head are spiny bracts
  • The name ‘nodding thistle’ comes from when the mature flower head falls off.

Consequences of invasion

  • Likes neutral to acidic soils and is a problem in grasslands where grazing animals favour grasses over the thistle, giving it an advantage
  • Outcompetes native grasses
  • Creates impenetrable thickets

How was it introduced? How does it spread?

  • Native to Europe, this thistle is known as a pest to rangeland
  • A thistle plant may produce up to 1200 seeds
  • Prefers to establish on disturbed sites.

Integrated Pest Management Options

  • Prevent seed production
  • Learn to properly identify nodding thistle
  • Clean equipment and gear before leaving an infested site
  • Dispose invasive species properly at designated disposal sites
  • Frequent cultivation
  • Hand digging and mowing over a period of time
  • Mowing just before seed to reduce seed production. Debris from mowing should be collected and burned

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