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Rangeland-Pasture Recommendations <br /> Russian knapweed Identification and <br /> Management <br /> ' Russian knapweed (Centaurea repens) is a non-native deep-rooted <br /> perennial that spreads by seeds and aggressive,creeping,horizontal roots <br /> t (rhizomes). The roots are black with a scaly appearance. Russian knapweed can <br /> grow up to 3 feet in height. The stems and leaves are covered with short, stiff <br /> hairs. The flowers are urn-shaped, pink to purple in color, and are solitary at the <br /> ' tips of the upper branches. Russian knapweed can be distinguished from other <br /> knapweeds by the pointed papery tips of the bracts that surround the flowers. <br /> Russian knapweed emerges from its root system in early spring after soil <br /> temperatures remain above freezing. It produces flowers from June to August <br /> and sets seed in later summer to early fall. Russian knapweed reproduces <br /> primarily from its root system. Buds on the horizontal roots can form <br /> adventitious shoots that may grow to be independent plants. Russian knapweed <br /> can be managed with herbicides or insects, but long-term control must include <br /> planting competitive plant species to occupy bare ground once infested by the <br /> ' weed. Flowerhead <br /> Smooth <br /> Russian knapweed is allelopathic, which means it contains a toxic <br /> substance that inhibits the growth of competing plants. This weed may also be <br /> ' toxic to horses resulting in serious injury or possibly death of the animal. Russian <br /> knapweed displaces native vegetation and reduces forage values on range and <br /> pasturelands. It can infest many land types,from roadsides, ditch banks, riparian <br /> ' zones,pastures, irrigated cropland,clearcuts, and cropland. <br /> The most effective method of control for Russian knapweed is to prevent <br /> its establishment through proper land management. Maintain healthy pastures <br /> ' and rangeland and continually monitor your property for new infestations. <br /> On the backside of this sheet are Russian knapweed management <br /> ' recommendations. If you have any questions, please contact the Weld County <br /> Public Works Dept.,Weed Division at(970) 304-6496 ext. 3770. Please visit our <br /> website www.weldweeds.org. <br />