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ca <br />r=4 <br />C'd <br />Updated on: <br />08/08 <br />Colorado Dept. of <br />Agriculture <br />Conservation <br />Services Division <br />700 Kipling Street <br />Suite 4000 <br />Lakewood, CO <br />80215 <br />303 - 239 -4100 <br />Rangeland, pasture, and riparian site recommendations <br />Russian knapweed Identification <br />and Management <br />Y4 <br />a <br />a: <br />Black, scaly <br />root <br />Identification and <br />Impacts <br />Russian knapweed (Acroptilon <br />repens) is a non - native deep - <br />rooted perennial that spreads by <br />aggressive, creeping, horizontal roots <br />(rhizomes) and seeds. The roots <br />are black with a scaly appearance. <br />Russian knapweed can grow up <br />to 3 feet in height. The stems and <br />leaves are covered with short, stiff <br />hairs. The flowers are urn - shaped, <br />pink to purple in color, and are <br />solitary at the tips of the upper <br />branches. Russian knapweed can be <br />distinguished from other knapweeds <br />by the pointed papery tips of the <br />rounded bracts that surround <br />the flowers. Russian knapweed <br />emerges in early spring after soil <br />temperatures remain above freezing. <br />It produces flowers from June to <br />August and sets seed in late summer <br />to early fall. Russian knapweed <br />reproduces primarily from its root <br />system. Buds on the horizontal roots <br />can form adventitious shoots that <br />can grow to be independent plants. <br />Russian knapweed is allelopathic, <br />which means it contains a toxic <br />substance that inhibits the growth <br />of competing plants. This weed may <br />also be toxic to horses resulting <br />in serious injury or possibly death <br />of the animal. Russian knapweed <br />displaces native vegetation and <br />reduces forage values on range and <br />pasturelands. <br />G <br />Habitats for Russian knapweed <br />includes many land types, from <br />roadsides, ditch banks, riparian zones, <br />pastures, irrigated cropland, clear cuts, <br />and cropland. <br />The most effective method of control <br />for Russian knapweed is to prevent <br />its establishment through proper land <br />management. Maintain healthy pastures <br />and rangeland and continually monitor <br />your property for new infestations. <br />If Russian knapweed is already <br />established, using an integrated weed <br />management approach proves to be <br />effective. Russian knapweed can be <br />managed with herbicides or insects, <br />but long -term control must include <br />planting competitive plant species to <br />occupy bare ground once infested by the <br />weed. Details on the back of this sheet <br />can help to create a management plan <br />compatible with your site ecology. <br />Russian knapweed is designated as <br />a "List B" species on the Colorado <br />Noxious Weed Act. It is required to <br />be either eradicated, contained, or <br />suppressed depending on the local <br />infestations. For more information, <br />visit www.colorado.gov /ag /csd and click <br />on the Noxious Weed Program link or <br />call the State Weed Coordinator at the <br />Colorado Department of Agriculture, <br />Conservation Services Division, 303- <br />239 -4100. <br />a..........�: ..�.— �.._ <br />Bracts photo at left, © Steve Dewey, Invasive. <br />org. Infestation map above, Crystal Andrews, <br />Colorado Department of Agriculture. All other <br />�1 <br />