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Page 7 of 23 <br />Chemical Control of Plumeless 'T'histle <br />Appendix 1 <br />Several herbicides are registered in pasture, rangeland and noncrop areas to control Plumeless thistle. <br />Tordon 22K (picloram), Curtail (clopyralid +2,4-D), ganveWanquish/Clarity (dicamba), 2,4-D, or <br />BanveWanquish/Clarity plus 2,4-D are commonly used. Apply these herbicides in spring or fall to <br />Plumeless thistle rosettes. <br />Apply Tordon at 0.5 to 1 pint per acre (A), Curtail at 2 quaris/A, Banvel/Vanquish/Clarity at 0.5 to 2 <br />quarts/A, 2,4-D at I.5 to 2 quarts/A, or BanvelNanquish/Glarity plus 2,4-D at 0.5 plus 1 quart/A. Cool <br />temperatures (below 50 degrees F), particularly in fall, may adversely affect 2,4-D control of Plumeless <br />thistle; therefore, use 2,4-D in spring. Tordon is largely unaffected by cool temperatures. <br />BanvelNanquish/Clarity can be adversely affected but less than 2,4-D. BanvelNanquish/Clarity plus 2,4-D <br />works well in spring or fall. Apply any of these herbicides before Plumeless thistle bolts or seed production <br />still will occur. <br />Ally-Escort (metsulfuron) or Telar (chlorsulfuron) also can be used. Use Telar in noncrop areas only and <br />Ally-Escort in pastures, rangeland or noncrop areas. Research from Colorado State University and the <br />University of Nebraska shows that Telar or Ally-Escort prevents or dramatically reduces viable seed <br />formation when applied in spring, up to early flower growth stages. The latest time to apply these <br />herbicides is when developed terminal flowers have opened up to the size of a dime. <br />Apply Telar at I ounce/A or A11y-Escort at 0.5 ounce/A. Add a good agricultural surfactant at 0.25 percent <br />v/v2 to Ally-Escort or Telar treatments or control is inadequate. <br />Scotch thistle <br />', . •~ ~ ..t i '.~, <br />4` 4~ .. : -~. ~ ~ <br />. ,~~ ~s <br /> <br />• <br />