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Page 1 I of 23 <br />Chemical Control of Russian knapweed <br />Appendix I <br />In most circumstances, an herbicide alone will not effectively manage. Russian knapweed. however, there <br />ntay 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 chenucal and <br />culturaIcon trol, avoid using herbicide rates that ni.mre grasses because effective competition will he <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 1 quamA or spot sprayed at rates up to 2 quarts; A. Tordon plus 2.4-D (I to 1.5 pints , I <br />quartiA) also will control Russian knapweed. I I low rates of Tordon or Tordon plus 2,4-D are used, <br />application for two consecutive years may he necessary to achieve adequate control. Apply Tordon any <br />time the weed is actively growing. <br />For Telar (chlonulfin'on), a noncrop herbicide that controls Russian knapweed, 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 brume species. Always add a good agricultural surfactant at 0-25 to 0.5 percent v/v to the <br />spray solution. Escort (ntetsulfturon) is labeled for pasture and rangeland use. Apply it at 0.75 to 1 ounce"A <br />with a good agricultural surfactant. Optimum timing for Escort is similar to Telar. <br />Mechanical Control of Russian knapweed <br />Russian knapweed tends to form monocultures and usually eliminates other plants. Therefore, sowing <br />desirable plait species is necessary after the weed is controlled. Smooth brome will compete with Russian <br />knapweed. Research shows that streambank wheatorass, thickspike wheatgrass, crested wheatgrass and <br />Russian wildrye established after Russian knapweed was suppressed with herbicides. Sod-forming <br />perennial grasses, like streambatk or thickspike \vheatgrasses, help prevcnt reimasion better than bunch <br />grasses like crested %%heatgrass. <br />If the Russian knapweed stand is not too old and grasses are still present. stimulating grass gmNyth by <br />irrigation (where possible) should increase grass competition with knapweed and keep the weed under <br />continual stress. <br />Spotted knapweed