Musk Thistle

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Musk Thistle

• Carduus nutans
• C. macrocephalus
• Sunflower family
• Biennial
• Reproduces only from seed
• Seed viable 8 to 10 years in soil
• Spring or fall emergence
• Found in at least 40 states
• Key to management success
• Prevent seed formation

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Rosette

• Leaves are dark green with light green midrib
• Lobed leaves with 3-5 points with a spine
• Germination favored on poorly vegetated sites

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Shoot biology

• In second year stems grow 2-6 ft tall
• Flowering shoots branched
• Seed production 45-55 days after bolting

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Distribution Musk Thistle
2005
1999
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The Thistles
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Biennial lifecyle
Spring(2)
Spring(1)
Fall(2)
Fall(1)
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Common management tools The thistles
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Musk Thistle Biological ControlRhinocyllus
conicus
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Musk Thistle Biological ControlRhinocyllus
conicus

• Attacks many Cirsium and Carduus species
• Including several TE species
• Originally predicted to attack numerous species
• Would NOT be introduced today
• Because of the success of this weevil nationwide
  we are no longer offering this beetle Biological
  Control of Weeds, Inc.