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Creator:: Oregon State University. Extension Service, Washington State University. Extension, University of Idaho. Extension, Roché, Cindy Talbott, Burrill, L. C., and Pacific Northwest Cooperative Extension
Abstract:: Squarrose knapweed, introduced from southwest Asia and the Middle East, became weedy in northern California and Utah by the early 1950s. How it was originally introduced is not known, but its spread in California and Utah was associated with the trailing of range sheep. Squarrose knapweed grows in the Klamath,...
Resource Type:: Technical Report
Full Text:: . Two insects introduced for biological control of diffuse and spotted knapweed also reduce seed

Creator:: Oregon State University. Extension Service, Larson, Larry, Sheley, R., McInnis, M., and Kiemnec, Gary L.
Abstract:: Yellow starthistle (Centaurea solstitialis L.) is a member of the knapweed (Centaurea L.) complex. It is poor forage for all livestock and causes “chewing disease,” a nervous disorder, in horses. Yellow starthistle infests millions of acres in California and the Pacific Northwest. Infestations range from scattered plants to dense stands...
Resource Type:: Technical Report
Full Text:: to reestablish following most initial control efforts. Seedlings Yellow starthistle typically

Creator:: Oregon State University. Extension Service, Roche, Cindy Talbott, and White, G. R. (George Randolph), 1958-
Abstract:: In the heat of summer in the Rogue Valley, yellow starthistle (Centaurea solstitialis) raises heads of brilliant yellow flowers rigidly defended by sharp spines. Although bees reap double benefits of nectar and pollen during a season when most native plants no longer are flowering, this nonnative weed is a threat...
Resource Type:: Technical Report
Full Text:: changed the mosaic of natural grasslands, oak woodlands, and chaparral. Grazing, logging, fire control

Creator:: Oregon State University. Extension Service
Abstract:: Knapweeds are a serious problem in Oregon because they vigorously invade disturbed or degraded sites and form dense populations that exclude native and desirable plant communities, causing economic and ecological losses. Their ability to spread rapidly by seeds and roots makes control very difficult. Seeds can remain viable for 5...
Resource Type:: Technical Report
Full Text:: , but they will reinvade the site without follow-up cultural control. Russian knapweed, with its very

Creator:: Detweiler, Amy Jo and Oregon State University. Extension Service
Abstract:: Four species of Centaurea are commonly found in central and eastern Oregon, including spotted knapweed (Centaurea maculosa), diffuse knapweed (Centaurea diffusa), Russian knapweed (Centaurea repens), and yellow starthistle (Centaurea solstitialis). These four species are a serious problem throughout Oregon and the Pacific Northwest. Stands of knapweed can choke out natural...
Resource Type:: Technical Report
Full Text:: Identification and Control of Knapweed Species in Central and

Creator:: Sturdevant, Nancy J., Dewey, Jerald E., United States. Forest Health Protection, and United States. Forest Service. Northern Region
Resource Type:: Technical Report
Full Text:: released as biological control agents of spotted knapweed, Centaurea maculosa Lamarck, in the United States

ScholarsArchive@OSU