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Diffuse
Knapweed - Centaurea diffusa
Family: Asteraceae
Description
Diffuse knapweed is a non-creeping, erect annual, biennial or sometimes shortlived perenial that reproduces and spreads exclusively from seed.
This species of knapweed can be mistaken for spotted knapweed, a slightly more common species that inhabits the same range.
Interesting facts (Inroduction)
Diffuse knapweed is an introduced plant from southern Europe to north-central Ukraine. It is a competitive plant in dry, light, porous soils in Europe and thus likes similar habitats in the United States. It is believed to have been introduced as a contaminant of alfalfa from Turkestan near the Caspian Sea. The first indication that it was in the US was from Washington in 1907.
Biocontrol
Several biological control agents, including a root boring beetle and moth, 2 seed head gall flies, and a seed head weevil are available but are not proven effective
Links to more information
Species info - From Colorado State University
Species Info - Idaho Invasive plant page
Information - complete information from the noxious weed board in washington state.
Website, video, and graphics by Rob Nelson
For more information on this plant or management please contact US Army Corp of Engineers
