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Recommended management methods: <br />Cultural - Establishment of selected, aggressive grasses can be an effective <br />cultural control of diffuse knapweed. Contact your local CSU Extension office or <br />Natural Resources Conservation Service office for seed mix recommendations. <br />Mechanical - Mowing the above -ground portion of the plant, before seed set <br />may be an effective way to reduce seed production. Mowings should be followed <br />by a fall herbicide treatment. Pulling can be effective on smaller infestations, but <br />must be done repeatedly. <br />Biological -- Biological control agents, such as the seed head weevil (Larinus <br />minutus) and the gall -forming fly (Uropliora affinis), are two of several species that <br />are effective at controlling Iarge infestations. When used together, these insects <br />provide fair to good control. Expect to wait at Ieast 3 to 5 years for the agents to <br />establish significant populations and achieve optimum management results. <br />Biocontrol agents can be obtained at no charge from the Colorado Department of <br />Agriculture's Insectary. Please call 970464-7916 or go to <br />www.palisadeinsectga.com for more information. <br />Diffuse knapweed is more likely to be grazed by sheep. The plants must be green <br />and succulent and the only forage available in order for sheep to graze it. <br />Herbicides - The following are recommendations for herbicides that can be <br />applied to range and pasturelands. Always read, understand, and follow label <br />directions. The herbicide label is the LAW? <br />Heib%aide <br />—Rate..A <br />". ca *6 nts <br />2,4-D Amine <br />1 qt./acre <br />Spring/fall rosette — before flowering stalk lengthens. DO NOT <br />or <br />apply when outside temperatures will exceed 85 degrees. <br />1 oz/gal water <br />Add non-ionic surfactant a 0.32 oz/gal water or <br />1 t/100 gal water. <br />Curtail <br />2 qts./acre <br />Spring rosette to pre -bud stage and/or fall rosette. <br />or <br />Add non-ionic surfactant c@ 032 oz/gal water or <br />2.0 oz/gal water <br />1 t/100 gal water. <br />Clarity <br />1 qt./acre <br />Spring rosette —before flowering stalk lengthens and/or late fall <br />or <br />treatment of rosettes. DO NOT apply near or under trees and/or <br />0.75 oz/ al water <br />shrubs or when outside temperatures will exceed 85 degrees. <br />Milestone <br />5 to 7 oz/ acre <br />Apply to plants in the spring rosette stage and/or to dormant <br />plants in the fall. If the plants are in the bud stage add 2,4-D at <br />32 oz/acre. It is permissible to treat seasonally dry wetlands and <br />transitional areas between upland and lowland sites. DO NOT <br />rotate to a broadleaf crop within 1 year of application: Add a <br />non-ionic surfactant -- 0.32az/ al water or l t1100 al water. <br />seedhead gall fly, Urophora quadrifasciata, <br />ie of many biocontrol agents available for <br />ase to control diffuse knapweed. <br />