Knapweed - Centaurea diffusa
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
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
info - From Colorado State University
- Idaho Invasive plant page
- 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