Russian Thistle

Russian thistle young plant
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Russian thistle plant Russian thistle plant Russian thistle stem and leaves
Russian thistle stem tip Russian thistle flowering


Russian thistle is an annual weed, reproducing by seeds. The stems are up to 1.2 m tall, red striped, and spread as much or more horizontally as vertically. The leaves are alternate, long, 2-5 cm, narrow, dark green, and fleshy. The later leaves are shorter, broader, and are tipped with stiff spines. The flowers are small, 2 mm wide, green or pinkish, inconspicuous, and occur in the axils of upper leaves. Two spiny-tipped bracts accompany each flower. The seeds are a cone shaped coiled utricle, 2 mm in diameter, dull brown to grey in colour.

Russian thistle can produce up to 200,000 seeds per plant. When mature it acts as a tumbleweed, rolling along with the wind spreading seeds as it travels. This weed is a high user of nitrogen and this can indirectly affect the growth of desirable plant species.

Scouting Techniques

Take a minimum of 20 weed counts across the field.

Effects On Crop Quality

Nitrates and soluble oxalates accumulate in the plants photosynthetic parts at levels poisonous to sheep.

Control Tips

  • Group 22 herbicide application in non-crop areas
  • mowing
  • cultivation
  • Groups 9 &10 in herbicide tolerant crops