The Enemy: Rush Skeletonweed (Chondrilla juncea L.) is a perennial plant that has infested several million acres in Idaho. Originally found in the early 80’s as a 5 acre patch near Horseshoe Bend in 20 years went to over 1 million acres. Noticeable leaves are found as rosettes which are sharply toothed like others in the Asteraceae family. Stem leaves are very small and inconspicuous and narrow, thus giving the plant the look of no leaves or skeletal in appearance. Flowering heads are found scattered on the branches, approximately ¾ inch in diameter. This plant resembles an alfalfa plant after a migration of grasshoppers has stripped all the leaves off. To tell the difference look at the base of the stems. If the stem has small red hairs on the lower 3 to 4 inches, where other plants do not, it will be this noxious weed. One can also look for the milky latex that is produced if the stem is broken.
The Strategy: The dandelion-like seeds float in the air for miles and miles. The plant is not foraged upon, invades very rapidly, which like the Boise National Forest, adds to its ability to destroy an ecosystem.
The Defense: Mechanical control is very difficult on this plant. Deep roots that may or may have rhizomes make it so that the growing parts of the roots are not destroyed. Herbicides such as Milestone®, Perspective®, Tordon 22K, or Transline are most effective when used in the fall or early spring. Once the plant has bolted, the basal rosettes recede, thus giving very little leaf surface to allow the pesticide to get into the plant. Hand harvesting the plants (if there are just a few of them) in the late summer will keep the seeds from spreading, then in early fall treating the plants with the herbicide is the most effective method of control.
PLEASE NOTE - The proper use and application of herbicides can be an effective way to control and eradicate noxious and invasive plants. Before using herbicides, always carefully follow the label and safety instructions on the label. While we recommend the use of herbicides as one of the effective tools for integrated pest management, the Idaho Weed Awareness Campaign assumes no liability for herbicide applications.
For more information, click on the link below to download the Idaho's Noxious Weeds Control Guidelines publication produced by the University of Idaho Extension.