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r aYlk?. <br />r , <br /> <br />"60d <br />V, J- <br />'?h <br />Mrs <br />PUW=ft bee" <br />Spotted knapweed germinates in spring or fall. Perennial <br />plants resume growth in early spring and bolt at approximately the <br />same time as diffuse knapweed. Flowering occurs through the <br />summer into fall. <br />Spotted knapweed is native to central Europe, where it is <br />found in light, porous, fertile, well-drained and often calcareous <br />soils in warm areas. It occupies dry meadows, pastureland, stony <br />hills, roadsides, and the sandy or gravelly fioodplains of streams <br />and rivers. Spotted knapweed tolerates dry conditions, similar to <br />diffuse knapweed, but survives in higher moisture areas as well <br />(e.g., it thrives in the wetter conditions of the western Montana <br />mountains). Spotted and diffuse knapweed infestations often occur <br />together in Colorado. <br /> Management <br /> Diffuse and spotted knapweed can be managed similarly. They are <br /> readily controlled with herbicides. However, the weeds will reinvade unless <br />Spotted knapweed infestations are not cultural techniques are used. <br />as severe in Colorado as diffuse Chemical control. Research conducted at Colorado State 1.lniversity <br />knapweed. However, this weed spreads indicates that Tordon 22K (pieloram) at 1 to 2 pt/A, Transline (clopyralid) at <br />rapidly. For example, spotted knapweed 0.67 to I pt/A, Curtail (clopyralid + 2,4-D) at 4 to 6 pt/A, or BanveV <br />was first observed in Gallatin County <br />Montana, in the 1920s, but is now <br />Vanquish/Clarity (dicamba) at 1 to 2 pt/A control diffuse knapweed. Tank <br />found in all Montana counties. Today, mixes of Banvel/Vanquish/Clarity plus 2,4-D at I pt + 2 pt/A or BanveV <br />over 4.7 million acres are infested. Vanquish/Clarity plus Tordon 22K at 1 to 2 pt + 0-5 to i pt/A or Tordon plus <br /> 2,4-D at 0.75 pt + 2 pt/A all control diffuse knapweed. These tank-mixes <br /> may save money and reduce grass injury resulting from higher use rates of a <br /> single herbicide. <br /> Spotted knapweed and diffuse knapweed generally occupy the same <br /> areas in Colorado, so the same herbicide treatments can be applied. Weed <br /> scientists at Montana State University indicate that I pt/A of Tordon (0.25 lb) <br />Livestock (sheep, goat, cattle) will eat controls spotted knapweed for two to three years, but the weed will reinvade <br />diffuse and spotted knapweed. Recent the area unless other management techniques are used. <br />research completed by Colorado State <br />universityshows that cattle grazing <br />Cultural control- If desirable grass competition is evident in diffuse <br />diffuse knapweed twice in spring or spotted knapweed stands, judicious herbicide application that. does not <br />decreased seed set by 50 percent and injure grasses may allow them to compete effectively with the weeds. <br />tumbling off-site over winter by 15 Irrigation (where possible) may help stimulate grass competition in these <br />percent Cattle were managed to cases. However, infested rangeland or pastures often are degraded, allowing <br />achieve 50 percent utilization of pasture knapweed invasion, and herbicides alone will not restore the land to a <br />and were allowed to graze at two 10- productive state. Seeding suitable perennial grasses is necessary to prevent <br />day intervals when diffuse knapweed weed reinvasion. <br />was bolting and about 6 to 12 inches Biological control. Many insects are being evaluated for biological <br />tall. control of diffuse and spotted knapweeds. Researchers at Montana State <br /> University believe it will take a complex of insects (perhaps 12) to reduce <br /> diffuse and spotted knapweed populations. <br />Colorado State University Cooperative Several insects are available in Colorado, from the Colorado <br />Extension weed specialist <br />silandence. professor, <br />plant pathology and weed <br /> <br />Department of Agriculture. The seedhead flies Urophora ajfrnis and U. <br /> quadrifasciata have been released in many Front Range counties. These <br />Issued in furtheranne of cooperative insects cause plants to produce fewer viable seeds and abort terminal or <br />Extension work, , Acts Ads of May 8 and June 30, <br />lateral flowers <br />1914, in cooperation with the U_S. . <br />Department of Agriculture, Milan A.Rewerts, Root-feeding insects may have a more detrimental effect on knapweed <br />Directorof Cooperative Extension, Colorado populations than seed-feeding ones. Larvae of the diffuse knapweed root beetle <br />State University, Fort Collins, Colorado. <br />Cooperative Extension programs are <br />(Sphenoptera jugaslavica) feed in the roots of diffuse knapweed. Larvae of the <br />available toaliwithoutdiscrimination.No yellow-winged knapweed moth (Agapeta zoegana) feed and the knapweed <br />endorsement of products mentioned is root weevil (Cyphocleonus achates) in the roots of both knapweed species. <br />intended nor is criticism implied of products <br />not mentioned.