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LIST B <br /> Spotted knapweed - Centaurea maculosa <br /> A short-lived perennial that reproduces only by seed. Each plant is capable <br /> of producing up to 40,000 seeds. It tends to invade disturbed / overgrazed <br /> areas, but can tolerate both dry conditions and high moisture areas. <br /> Identification: <br /> • Flower: Urn-shaped, pink to purple, usually single at the end of <br /> branches; black-tipped ("spotted") spiny bracts. <br /> • Leaves: Small, oblong, pinnately divided. <br /> • Root: Stout taproot. <br /> Control methods: <br /> Biological: <br /> The insects listed below are available for control: <br /> Root weevil - Cyphocleonus achates <br /> Seedhead weevil - Larinus minutus <br /> Mechanical: <br /> Dig when the soil is moist, removing all roots. Mow at full bloom to <br /> stress the plant; all parts must be disposed of properly, as seed may <br /> still develop on cut plants. <br /> Chemical: <br /> Clopyralid + 2,4-D: Apply to spring or fall rosettes. <br /> Clopyralid: Apply in spring before bolt stage occurs or in fall <br /> to the rosettes. <br /> Aminopyralid: Apply in spring at the rosette to early bolt stage <br /> and /or in fall to the rosettes. <br /> *Picloram: Apply in spring through mid-bolt or in fall to the <br /> rosettes. <br /> *Restricted-use chemical 50 <br />