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Italian thistle is an annual plant and therefore it reproduces entirely by seed. Wind is the primary means of dispersal for Italian thistle. Its seeds germinate very easily and do not need a long dormancy period. The seedlings grow most easily on bare and disturbed soils, and they can remain viable in the soil for up to eight years. ManagementItalian thistle is a common weed in disturbed sites below 1500 meters (5,000 feet) in Sequoia National Park. It is most common within and adjacent to roads and campgrounds. It is also scattered throughout the less-disturbed blue oak woodland, gaps in chaparral stands, and riparian areas. In 2002 Sequoia and Kings Canyon Natural Resource Management personnel began actively eradicating Italian thistle with the goal of containing the species to below 850 meters (2,800 feet). The species is being mapped to determine the extent of invasion in the Kaweah River Drainage. Control is by manual removal and spot application of approved glyphosate herbicide. Follow-up surveys and eradication efforts will be undertaken in future years to exhaust the stored seed bank of this annual species. In 2003, a few individuals of this species were detected in the Cedar Grove area of Kings Canyon National Park. Italian thistle was previously not known to be present in Kings Canyon. Keeping this species from spreading in Kings Canyon is a high priority. If you find a plant in Kings Canyon that you suspect is Italian thistle, please report it immediately. Remember, do not remove any plants in the park--non-native plants can easily be mistaken for valuable natives. |
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Last Updated
September 17, 2003
Email Contact: Athena Demetry
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