Rush Skeletonweed

Identification tips:

  • Deep-rooted, perennial forb in the sunflower family (Asteraceae)
  • Grows 1-4 feet tall and produces milky latex when broken
  • Highly branched stem, few leaves = ’skeletal’ appearance
  • Stiff, downward-pointing hairs near the base of stem
  • Small, yellow flowers at ends of stems, either individually or   clusters
  • Overwinters as rosette which resembles common dandelion

Habitat: Roadsides, rangelands, pastures, grain fields, disturbed sites (e.g., recent wildfire or cheatgrass-invaded sites).

History: Rush skeletonweed is native to Asia, the Mediterranean, and North Africa. It was first reported in the United States near Spokane, Washington in 1938. A small infestation was found in Sanders County, Montana in 1991 and has subsequently been reported in Lincoln, Flathead, and Treasure Counties as well. Most recently, it has been reported in Beaverhead and Ravalli counties.  It is listed as a Priority 1B noxious weed in Montana.

Spread: Rush skeletonweed primarily disperses by seeds; established plants are capable of producing 15,000-20,000 seeds. The small, lightweight seeds can spread far distances by wind and water and can also attach to animals and clothing. It can also reproduce vegetatively from fragmented taproots.

Impacts: Rush skeletonweed competes for soil moisture and nutrients with grains in cropping systems and desired plants in rangeland. It rapidly spread through the wheat-growing area of southeastern Australia and caused significant yield reductions. It can form dense monocultures on rangeland, reducing forage for cattle and wildlife.

Management: Rush skeletonweed is a high priority species for Montana due to its limited presence here and our close proximity to large infestations in Idaho. Furthermore, it could have devastating impacts on agriculture in Montana if it becomes well established. Management priorities for rush skeletonweed include monitoring, early detection, and treatment of newly invading plants. Hand-pulling is an option for small infestations, but this requires control 2-3 times per year for more than five years. Integrating various management techniques such as prevention, monitoring, reseeding and herbicides can help reduce the invasion of rush skeletonweed. If you think you have found rush skeletonweed, contact your Extension agent or county weed coordinator immediately.

 

photo source: malag.aes.oregonstate.edu