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rush skeletonweed (Chondrilla juncea)
ODA rating: B and T

Oregon rush skeletonweed distribution
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Image courtesy of Arnie Grammon, Baker County. 

Image courtesy of Greg Winans, Tri-County Weed.

Image courtesy of Rich Old, XID Services.
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Perennial; blooms July to September. Grows 1 to 4 feet tall. Yellow flower 3/4 inch in diameter with 7 to 15 petals. Coarse downbent hairs on the lower 4 to 6 inches of stem; almost no leaves. Spreads primarily by seed, but roots scattered by cultivation can aid in spread.
Rush skeletonweed is an aggressive plant in both rangeland and cropland, particularly in light textured soil and has been the target of large control projects for decades. Cereal grain and potato production areas are at risk from skeletonweed invasion. Impacts include reduced yield due to competition and harvest difficulties with combine harvesters from latex sap that is exuded from the plant. Extensive efforts have been made to eradicate or contain outbreaks, but new sites are being found each year in the eastern part of Oregon.
Native to Eurasia, this noxious weed now infests several million acres in the Pacific Northwest and California including Idaho.
Distribution in Oregon
The first documented site in Oregon was 1974 in Douglas County.

Biological controls
Four biocontrol agents are approved for release. Three of these, a gall midge, a gall mite and a rust fungus, have been established in Oregon, but have only been effective in reducing seed production.