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and hay meadows. The key principle to Canada thistle control or any creeping perennial is to <br />stress the plant. It is essential to develop a sound management plan implemented over several <br />years to be successful. <br />Grasses and alfalfa can effectively compete with Canada thistle if desirable plant growth is <br />favored by good management. There are several good herbicides for Canada thistle including, <br />Tordon, Banvel, and 2,4-D. Mowing can be effective if combined with herbicide treatment. <br />Ceutorhyncus litura is a weevil currently used as a biocontrol agent in Colorado. The weevil <br />alone will not effectively control the thistle. Therefore, it must be combined with other methods <br />to be successful. Research has shown that biological and chemical control are compatible for <br />musk thistle and most likely will occur for Canada thistle. Additional information about Canada <br />thistle was obtained from the CSU Extension Office and is included as an appendix to this plan. <br />The information includes a description of the plant, plant reproduction, management, and how to <br />integrate the recommended control methods. <br />Musk thistle <br />Musk thistle is an aggressive weed of pastures, rangeland, roadsides and non-crop areas. I[ is a <br />biennial wee, although occasionally it is an annual. Since musk thistle reproduces solely from <br />seed, the key for successful management is to prevent seed production. Vigorously growing <br />grass competes with musk thistle and fewer thistles occur in pastures where grazing is deferred. <br />However, musk thistle can become a problem in pasture or on rangeland that is in good <br />condition. A successful management system combines control methods. Maintaining pastures <br />and rangeland in good condition is a primary factor for musk thistle management. Musk thistle <br />will not tolerate tillage and can be removed easily by severing the root below ground. Mowing <br />can effectively reduce seed output if plants are cut when the in the flowering stage. Several <br />herbicides are used to control musk thistle in pasture, rangeland, and non-crop aeeas. Tordon, <br />Banvel, or 2,4-D are commonly used. The musk thistle seed head weevil can be found <br />throughout Colorado and are effective in reducing seed production, but if used alone are not an <br />effective management tool. Applying herbicides at a time that does not interfere with insect <br />development is an effective combination of control methods. For small infestations and single <br />12 <br />