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. - <br />'r' >~ <br />rr , <br />~~+~~ <br />4 <br />~~~ <br />~t <br />'f~:.. ; t~t.:. <br />,:, j"~~...., <br />.. • a .. <br />y..,, <br />6patket ~;x~fff <br />`~- - <br />l4e~nrlp~ hrtda <br />Spotted knapweed germinates in spring or fall. Perennial <br />plants resume growOr in eazly 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 tloodplains of streams <br />and rivers. Spotted knapweed tolerates dry conditions, similaz 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 aze <br /> readily controlled with herbicides. However; the weeds will reinvade unless <br />Spotted knapweed inlesfafions are not cultural techniques are used. <br />as severe rn Colorado as diffuse CLemical conro4 Research conducted at Colorado State University <br />knapweed. However, this weed spreads indicates that Tordon 22K (picloram) at 1 to 2 pUA, Transline (clopyralid) at <br />mPtaN- Far example, spotted knapweed 0.67 to 1 pUA, Curtail (clopyralid + 2,4-D) at 4 to 6 pUA, or BanveU <br />was first observed in Gallatin County, <br />Montana, in ttie 1920s, but is now Vanquish/Clarity (dicamba) at 1 to 2 pUA control diffuse knapweed. Tank <br />found in all Montana counties. Today, mixes of BanvelNanquish/Clarity plus 2,4-D at 1 pt + 2 pUA or BanveV <br />over 4.7 miAion acres are ;Wrested. VanquishlClarity plus Tordon 22K at 1 to 2 pt + 0.5 to 1 pUA or Tordon plus <br /> 2,4-D at 0.75 pt + 2 pUA all control diffuse knapweed. These tank-mites <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 /> aeeas in Colorado, so the same herbicide treatments can be applied. Weed <br /> scientists at Montana State University indicate that 1 pUA of Tordon (0.25 lb) <br />Livestock (sheep, goats, cattle) wilt eat controls spotted knapweed for two to three yeazs, but the weed will reinvade <br />diffuse and spotted knapweed. Recent the area unless other management techniques are used. <br />research completed by Cdorado State Cultural control If desirable grass competition is evident in diffuse <br />University shoes that cattle grazing <br />diffuse knapweed twice in spring <br />or spotted knapweed stands, judicious herbicide application that does not <br />decreased seed set by 50 percent arai rnJLLTe grasses may allow them to compete effectively with the weeds. <br />tumbling o/f-site over winter by t5 Irrigation (where possible) may help stimulate grass competition in these <br />percent. Catde were managed to cases. However, infested rangeland or pasttues often aze degraded, allowing <br />achieve 5o percent usfizaGon of pasture knapweed invasion, and herbicides alone will not restore Ute land to a <br />arrd ware allowed m graze at too fa productive state. Seeding suitable perennial grasses is necessary to prevent <br />day intervals when diffuse knapweed weed reinvasion. <br />was boning afro' about s m f2 inches Biological control Many insects are being evaluated for biological <br />talt 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 />~Cororadosrateuniwrsi(yrooperative Several insects are available in Colorado, from the Colorado <br />r=xtension weed speaatisr and professor. Department of Agriculture. The seedhead flies Utaphora ajjinis and U. <br />plant pamorogy and weed silence. <br />quadrijasciata have been released in many Front Range counties. These <br />Issued in furtherance cf Cooperative insects cause plants to produce fewer viable seeds and abort terminal or <br />Extension work, Ads of May 8 and June 39, lateral flbwe75. <br />1974, in cooperation with the U.S. <br />oeparlmemotneer.,,hore,MiianA.ftewart~, <br />Root-feeding insects may have a more detrimental effect on knapweed <br />Director oFCooperative Exension, Cobrado populations than seed-feeding ones. Larvae of the diffuse knapweed root beetle <br />state unitersiry, Fort Cdl;ns, Colorado. (gphenoptera jugoslavica) feed in the roofs of diffuse knapweed. Larvae of the <br />Cooperative Extension programs are <br />available to allwithou[discrimination.No <br />yellow-winged knapweed moth (Agapera zoegana) feed and the knapweed <br />erMorsemant olproduds mentioned is root weevil (Cyphocleorrus achates) in the roots of both ]mapweed species. <br />intended nor is txiticism implied of products <br />trot merrdOrred. <br />