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Routt County Web Site <br />and diffuse knapweed also require control. For pictures, descriptions, and key differences <br />among the vazious knapweeds, see the of Routt County web site, http://co.routt.co.us and <br />look under "Weed Control." <br />Distribution: <br />The only known infestations of meadow knapweed in Routt County and Colorado are on <br />RCR 129 near Mad Creek. It grows mainly in moist sites and may be in other areas of the <br />county. If you find any infestations please contact Routt County Weed Control as soon as <br />possible at: 970-870-5246. <br />Biology: <br />Meadow knapweed grows mainly on moist sites-irrigated pastures, moist meadows <br />and riparian areas. <br />It is a perennial plant, growing from a woody root crown. <br />Reproduction is mostly by seed, but the crown can re-sprout if mowed or pulled. <br />Control: <br />Prevention and early detection are critical for control! <br />• Practice good pasture management, avoid overgrazing, irrigate and fertilize as needed, <br />and reseed bare ground. A healthy pasture will help resist weed invasion. <br />• Use weed-free hay and seed and avoid bringing in weed-contaminated soil. <br />• Clean equipment that has been used in infested areas. <br />. Remove seedlings when young -newly established plants can usually be pulled <br />without leaving root fragments in the ground. <br />. Replant newly weeded areas with desirable (preferably native) plant species that will <br />discourage reinfestation. Grasses are especially helpful in fighting weeds. <br />. Dispose of weeds properly -bag or burn seed heads or fragments that may resprou[. <br />. Monitor the site for several years, promptly removing new seedlings. <br />HANDPULLING/DIGGING works best when the soil is moist. This method can be time <br />consuming because the root system is usually extensive; and is only effective for new or <br />small infestations. It may also create more disturbance which will be prime weed habitat. <br />Hand pulling is not recommended unless it can be done intensively for several years. The <br />plants must not be allowed to go to seed, and the site should be monitored for at least five <br />yeazs. If pulled be sure and get the entire root. <br />MOWING will slow, but not stop the spread of knapweed. Plants that are periodically <br />mowed continue to flower and produce seed on shorter plants, prolonging the season of <br />growth and flowering. Mowing is not recommended for meadow knapweed. <br />BIOLOGICAL CONTROL The seed head gall fly, Urophora quadrifasciata, attacks the <br />flower heads and lowers seed production, but will not destroy the plant. It needs large <br />infestations of knapweed to survive, and, since the only known infestation in Routt County is <br />small, is not recommended. <br />HERBICIDES can be effective, but should always be applied with care. Read and follow all <br />labeled instructions. Read the label to check that you are applying an herbicide in the right <br />Page 2 of 3 <br />file://C:\Documents and Settings\slse\Local Settings\Temp\Meadow Knapweed.htm 2!27/2006 <br />