• Canada Thistle Plant 215x150

Category C Weed

Sunflower family (Asteraceae)

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Canada thistle (Cirsium arvense)


    • Up to 4 ft. tall, green to brown, branched at the top and usually lacks hair (glabrous)


      • Alternate, oblong or lance-shaped, 2-8 in. long, shiny and lack hair; NO leaf stems (petioles); leaf edges (margins) are wavy, lobed or toothed with spiny edges


        • Pink, purple or white; occur in clusters at the ends of branches; base of flower is vase-shaped, 0.5-0.75 in. wide, lacks prickles and is covered with green to purple bracts with dark tips


          • Deep, extensive creeping root system


            • Grows best in moist areas; often found in pastures, hay fields, waste areas and along waterways; known to occur in all Nevada counties except Esmeralda

            • Perennial; reproduces by both roots and seed; plants often appear in patches or colonies due to the spreading root system


              • Repeated mowing, tillage, cutting or hand removal prior to seed production can provide suppression

              • Several biological control agents are available

              • Apply picloram, aminopyralid or clopyralid to actively growing plants through flowering; repeated applications of 2,4-D, dicamba or glyphosate to actively growing plants