PEST STATUS OF WEED

• Main Authors: L. -t. Kok, A. Gassmann, Bull Thistle, Cirsium Vulgare (savi Tenore
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: British Columbia; Canada; Newfoundland; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.565.791; http://www.invasive.org/weedcd/pdfs/biocontrol/19BullThistle.pdf

vasive thistle from Eurasia, found throughout the United States and in Canada from Newfoundland to British Columbia. It is capable of invading fields, pas-tures, wastelands and along roadsides, but will not survive in cultivated fields. Nature of Damage Economic damage. Bull thistle occurs in overgrazed pastures, where heavy infestations can exclude live-stock from infested areas. It also is common along roadside and vacant fields. Ecological damage. Although bull thistle is a problem predominantly in disturbed areas, it also can be found in natural areas. The basal rosette may grow to nearly 1 m in diameter before bolting, and, once established, bull thistle outcompetes native plant spe-cies for space, water, and nutrients. Geographical Distribution Bull thistle was introduced into the eastern United States several times during the 19th century. It is now established in all 48 contiguous states as well as Alaska and Hawaii (USDA, NRCS, 1999). It has been des-ignated as a noxious weed in Maryland, Pennsylva-