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Page I1 ol'23 <br />Chemical Control of Russian Knapsseed <br />Appendix <br />In most circumstances, an herbicide alone will not effectively manage Russian knapweed. however, there <br />may be situations where desirable plants within a Russian knapweed infestation may compete effectively <br />with the weed if it is stressed with a single weed management technique. When integrating chemical and <br />cultinal control. avoid :wing hcrhlclde ?ites that itmne grasses heeause rthecto c competition \k ill hr <br />reduced <br />Russian knapweed is controlled with Tordon 22K (picloram) at I to 2 quarts/A. Tordon may be broadcast <br />sprayed up to l quarVA or spot sprayed at rates up to 2 quarts, A. Tordon plus 2.4-D ( I to 1.5 pints i I <br />quart. A) also will control Russian knapweed. if low rates of Tordon or Tordon plus 2,4-D are used, <br />application for two consecutive years may be necessary to achieve adequate control. Apply Tordon any <br />hmc the weed is actively L_ROwing. <br />For Telar (chlorsulfuron), a noncrop herbicide that controls Russian knap weed, application timing is <br />critical. Apply ( I ounce/A) when Russian knapweed is in the bloom to postbloom stage. Earlier <br />applications do not control the weed effectively. Fall is a good time to apply Telar, but it may injure smooth <br />brome or other hrome species. Always add a good agricultural surfactant at 0.25 to 0.5 percent wv to the <br />spray solution. Escort (mctsulfaron) is labeled for pasture and rangeland use. Apply it at 0.75 to 1 ounce/A <br />with a good agricultural surfactant. Oplimunt timing for Escort is similar to Telar. <br />Mechanical Control of Russian Knapneed <br />Russian knapweed lends to form monocultures and usually eliminates other plants. Therefore, sowing <br />desirable plant species is necessary after the weed is controlled. Smooth hrome will compete with Russian <br />knapweed. Research shows that streambank wheatgrass, thickspike wheat grass, crested wheatgrass and <br />Russian wildrye established after Russian knapweed was suppressed with herbicides. Sod-forming <br />perennial grasses. like streambank or thickspike wheatgrasses, help prevent reinvasion better than hunch <br />grasses like crested wheatgrass. <br />If the Russian knapweed stand is not too old and grasses are still present. stimulating grass growth by <br />irrigation (\%,here possible) should increase grass competition with knapweed and keep the weed under <br />continual stress. <br />Spotted knapweed