Diffuse knapweed centaurea diffusa, also known as white knapweed, is a member of the genus centaurea in the family asteraceae. It is native to asia minor turkey, syria, the balkans, bulgaria, greece, romania, ukraine, and southern russia. Spokane county nwcb fact sheet on diffuse knapweed. This book was published by fhtet as part of the technology transfer.
Effects of postfire conditions on germination and seedling success of diffuse knapweed in northern arizona. Report on diffuse knapweed from the book weed control in natural areas in the western united states stevens county nwcb fact sheet on diffuse and spotted knapweed. The weevil is a biological control for both diffuse and spotted knapweed, a noxious weed in central oregon. Diffuse knapweed is an annual or biennial plant, generally growing to between 10 and 60 cm in height. Gerlach jd, rice kj 2003 testing life history correlates of invasiveness using. A species profile for diffuse knapweed, white knapweed, spreading knapweed, tumble knapweed from usda, national invasive species information center. Jim story, an entomologist at montana state university, has gone to central and. This plant may be known by one or more common names in. We thank christina kuykendall, jim story, sandy kegley, and nancy sturdevant for. During the first year of growth, diffuse knapweed appears as a rosette in spring or fall. Wicked weed of the west science smithsonian magazine. Ecology and management of diffuse knapweed centaurea diffusa. A biennial is a plant that completes its life cycle within two years.
These three knapweeds already infest more acreage than leafy spurge in montana and minnesota, and have been found in over 20 counties in north dakota. Diffuse knapweed is a biennial or shortlived perennial with a deep taproot in the aster family that is similar to the more common spotted knapweed, but is generally shorter and its upper stems have numerous spreading branches giving the plant a ball shape. What you need to know about the knapweed root weevil. Thurston county nwcb fact sheet on diffuse knapweed. Centaurea diffusa, also known as diffuse knapweed, white knapweed or tumble knapweed, is a member of the genus centaurea in the family asteraceae. Flowerheads are usually white sometimes pink to purple and are solitary or in clusters. Impacts of the biological control agent cyphocleonus achates on spotted knapweed, centaurea. Diffuse knapweed has been identified as a strong competitor. Distribution, biology, and management of diffuse knapweed. Native to the mediterranean region, diffuse knapweed was first recorded in montana. Prohibited noxious, class 1 in the canadian weed seeds order, 2016 under the seeds act.
Its characteristics and history, plus alternative weed control strategies. Diffuse knapweed is successful in its novel range primarily because the organisms and conditions that prevent it from. All imported and domestic seed must be free of prohibited noxious weed seeds. Its one of the good guys you should feel a pang of guilt about if you use herbicides. Spotted knapweed is driving out native plants and destroying rangeland. This species is common throughout western north america but is not actually native to the north american continent, but to the eastern mediterranean. Centaurea diffusa, also known as diffuse knapweed, white knapweed or tumble knapweed, is a. Members of this trio include spotted, diffuse, and russian knapweed. Diffuse knapweed national invasive species information. This book was published by fhtet as part of the technology transfer series. Centaurea diffusa wikibooks, open books for an open world. Diffuse knapweed is a nonnative biennial forb that reproduces solely by seed.
A weed report from the book weed control in natural areas in the. Franklin county nwcb fact sheet on diffuse knapweed. Plants profile for centaurea diffusa diffuse knapweed. North dakota is being threatened by three noxious weeds that could infest more acreage in the state and at a faster rate than leafy spurge. Both diffuse and spottted knapweed are typically annual, sometimes biennial or shortlived perennial, thus they reproduce mostly by seed. Pdf sustainable control of spotted knapweed centaurea stoebe. Biology and biological control of knapweed invasive. Spotted knapweed is a bushy biennial to shortlived perennial, to 3 ft tall, with a long.
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