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Page 8 of 23 <br />Management <br />Cultural control of Scotch Thistle <br />Appendix 1 <br />Maintaining pastures and rangeland in good condition is a primary factor for scotch thistle management. To <br />favor pasture and rangeland grass growth, do not overgraze. Fertilize only when necessary and according to <br />soil testing recommendations. To successfully manage Scotch thistle, prevent seed formation. <br />Mechanical control of Scotch Thistle <br />Scotch thistle will not tolerate tillage and can be removed easily by severing its root below ground with a <br />shovel or hoe. Mowing can effectively reduce seed output if plants are cut when the terminal head is in the <br />late-flowering stage. Gather and burn mowed debris to destroy any seed that has developed. <br />Chemical Control of Scotch Thistle <br />Several herbicides are registered in pasture, rangeland and noncrop areas to control Scotch thistle. Tordon <br />22K (picloram), Curtail (clopyralid +2,4-D), Banvel/Vanquish/Clarity (dicamba), 2,4-D, or <br />Banvel/Vanquish/Clarity phis 2,4-D are commonly used. Apply these herbicides in spring or fall to Scotch <br />thistle rosettes. <br />Apply Tordon at 0.5 to 1 pint per acre (A), Curtail at 2 quarts/A, Banvel/Vanquish/Clarity at 0.5 to 2 <br />quarts/A, 2,4-D at 1.5 to 2 quarts/A, or Banvel/Vanquish/Clarity 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 scotch thistle; <br />therefore, use 2,4-D in spring. Tordon is largely unaffected by cool temperatures. Banvel/Vanquish/Clarity <br />can be adversely affected but less than 2,4-D. Banvel/Vanquish/Clarity plus 2,4-D works well in spring or <br />fall. Apply any of these herbicides before scotch thistle bolts or seed production still will occur. <br />Alty-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 1 ounce/A or Ally-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.