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Management <br />Diffuse and spotted knapwced can be managed similarly. f hes are readily controlled with herbicides llowevcr, the <br />weeds wI Il reinvade unless cultural techniques are used <br />Chemical Control of Diffused knapweed <br />Research conducted at Colorado State university indicates that Jordon 22K (picloram) at 1 to 2 pt'A, I rinsline <br />tclopvralid) at 0.67 to I ptA, Curtail (clopyralid ; 2.4 -1)) at 4 to t, pt A. or 13arwel'Vanquish ( Iarity (dicamba) at 1 to 2 <br />pfA control diffuse knapwced. Tank mixes of I plus 2,4 -I) at 1 pt 2 pt A or <br />lianvel'Vanquish1C'Iarity plus Tordon 22K at 1 to 2 pt = 0.5 to 1 pt A or Cordon plus 2,4-1) at 0 75 pt . 2 p all <br />control diffuse knapwced ('hose tank -mixes may save money and reduce grass injury resulting from higher use rates of <br />a single herbicide <br />Spotted knapweed and diffuse knapweed generally occupy the same areas in Colorado, so the same herbicide treatments <br />can be applied Weed scientists at Montana State t iniversity indicate that 1 ptiA of Tordon (0.25 lb) controls spotted <br />knapweed for two to three years, hut the weed will reinvade the area unless other management techniques are used. <br />Mechanical Control of Diffused Knapweed <br />If desirable grass competition is evident in diffuse or spotted knapweed stands, judicious herbicide application that does <br />not injure grasses may allow them to compete effectively with the weeds. Irrigation (where possible) may help stimulate <br />grass competition in these cases. However, infested rangeland or pastures often are degraded. allowing knapweed <br />invasion, and herbicides alone will not restore the land to a productive state Seeding suitable perennial grasses is <br />necessary to prevent weed remvasion <br />