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Common Tansy Common Tansy (Tancetum vulgare), also known as golden buttons and garden tansy, is a perennial herb in the sunflower family. The plant readily invades roadsides, fence rows, pastures, stream banks, and waste areas throughout North America. While it is not a statewide noxious weed, it has been declared noxious in Broadwater, Beaverhead, Gallatin, Silverbow, Meagher, and Carbon counties. Mature common tansy plants are easily recognized by the flat-topped clusters of small, button-like, yellow flowers they bear in the summer. Stems grow in large clusters up to 6 feet high and are mostly hairless, often purplish-red in color, and extensively branched towards the top. Leaves are finely divided into leaflets giving the plant a fern-like appearance. Common tansy has a strong odor when crushed. Common tansy, native to Europe, has a long history of medicinal use. It was first introduced to North America for use in folk remedies and as an ornamental plants. Use of common tansy led the governor of Massachusetts to list common tansy as a necessary plant for colonial herb gardens in the 1600s. This led to widespread cultivation of the plant and its inevitable escape into fields and roadsides. By the 1800s this weed was growing wild throughout the Northeast. In 1912, it was reported as far west as Kansas and it was widespread in California by 1952. Limited research on control of common tansy has been conducted. As with most weeds, prevention of the establishment and spread of infestations is the most cost-effective management tool. The most effective herbicide for common tansy control is metsulfuron (Escort). In herbicide trials in northern Idaho, metsulfuron applied at 0.3 oz/acre yielded 99% control after three months and 98% control 15 months after treatment. Metsulfuron should always be used with a high quality, nonionic surfactant to ensure penetration of the herbicide into plant tissues. Picloram (Tordon) also provides good, short term control of common tansy. Neither of these herbicides should be used to control common tansy infestations near water as these chemicals are persistent in soil, and have potential to leach into groundwater. Accordingly, metsulfuron and picloram should not be used on any site where the depth to water table is less than 20 feet. This limits the usefulness of these chemicals for control of common tansy because the plants often grow near waterways. (Rodeo) and 2,4-D amine are alternative herbicides for use near water, but they are not very effective for controlling common tansy. Mowing provides an alternative to herbicide use near waterways, and has been reported to marginally control common tansy. ---PAGE BREAK--- Common tansy contains alkaloids that are toxic to both humans and livestock if consumed in large quantities. Cases of livestock poisoning are rare, though, as tansy is unpalatable to grazing animals. Source: MSU Extension Service