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Houndstongue (Cynoglossum officinals) is a biennial and very toxic to livestock, <br />especially horses. It causes irreversible liver damage and is an accumulative poison. <br />Early signs of poisoning in horses may include photosensitivity and blistering and peeling <br />of skin on the nose and lips. It forms a low growing rosette the first year and the second <br />year bolts up to 1-2 feet tall, forming rosy -purple flowers followed by a large, flat seed <br />that sticks to almost anything with Velcro -like hooks. It can be controlled with <br />herbicides or by cutting the roots at least 4 inches below the surface with a shovel once it <br />has bolted. Escort at 1.5 oz/acre or Telar at 1 oz/acre, especially if mixed with 1 qt <br />2,4-D/acre results in very good control. Use a non-ionic surfactant. Tordon or Banvel at <br />24 oz. per acre, or 2, 4-D amine at 1 quart per acre and a good quality surfactant all <br />provide good control. Spring or fall treatments are best. <br />Canada thistle (Cirsium arvense) is a deep rooted perennial that reproduces both <br />vegetatively and by seed. It forms dense stands, usually reaching a height of 2 to 4 feet <br />with small bluish -purple flowers. It readily appears throughout the County whenever the <br />ground is disturbed. Milestone at 5 oz/acre for young plants or 7 oz/acre for well <br />established infestations is the best treatment available. Spring and fall applications are <br />both effective. Spray it in the spring with 1 quart of Tordon, Banvel or Curtail per acre. <br />It is especially helpful with Canada thistle to re -seed any areas that are disturbed with a <br />good grass mix. Fall applications work well, but only if the plants are mowed in the <br />summer. <br />Musk thistle (Carduus nutans) is a biennial, which reproduces from seed. The first year's <br />growth is a large, compact rosette. 'Individual plants are effectively controlled with a <br />shovel. The second year the plant bolts, growing to a height of two to six feet, with large <br />spiny leaves with a deep green color. Flowers are large, nodding and purple. A biennial, <br />musk thistle responds well to mechanical control and can be either disked or mowed. <br />Musk thistle also responds well to herbicide control: Milestone at 5-7oz/acre is very <br />effective on musk thistle. Escort at 314 oz per acre; 2,4-D amine at 1 quart per acre; <br />Banvel or Tordon at 1.5 pints per acre; Curtail at 1 quart per acre. <br />Bull thistle (Cirsium vulgare) and Scotch thistle (Onopordum acanthium) are biennials, <br />and can be treated the same as musk thistle. These weeds are also best controlled with <br />Milestone at 5-7oz/acre, applied in late summer -early fall on first year rosettes or early in <br />the season of the second year before rosettes bolt. <br />Cheatgrass (Bromus tectorum) is a highly invasive annual or winter annual grass, and is <br />the subject of considerable research on effective controls due to its impact on Great Basin <br />rangelands. Aminocychlopyraclor as Matrix has been found to be effective when <br />applied according to specific label directions. Roundup (glyphosate), Journey, Plateau <br />and Landmarke may also be effective when used according to label directions. Though <br />this weed was not observed the site should continue to be monitored for its presence. <br />5 <br />