Rush Skeletonweed

Identification & Biology
Alias' : skeletonweed, gum succory, devil’s-grass, naked weed, hog-bite
Latin Name : Chondrilla juncea
Category : Terrestrial Plants
Description :

Heavily branched perennial, growing to 1.3 m tall
• Deep taproot, up to 2.5 m in the soil with one or more lateral roots in the upper 2 feet of soil
• Several branched wiry stems with stiff hairs
• Stems contain a milky latex juice
• Rosette leaves resemble common dandelion and are hairless with deep, irregular teeth that point back toward the leaf base
• Leaves are small, giving the plant a ‘skeleton-like’ appearance
• Small yellow flowers occur at the ends of stems, either individually or in groups of 2-3
• Seeds are nearly black and have a white featherlike hairs

Rush skeletonweed reproduces by seed and vegetatively from roots. A single plant may produce as many as 15,000-20,000 seeds. Seeds are easily dispersed by wind, water, animals and humans.

Look-a-likes: Rush skeletonweed can easily be misidentified in the rosette stage with hawksbeard, dandelion, prickly lettuce and various mustards. At maturity, rush skeletonweed can be confused with the intoroduced plant chicory (Cichorium intybus) and the native plant wire lettuce (Stephanomeria tenuifolia). Distinguishing characteristics of rush skeletonweed are: a) leaves with a smooth, even surface b) leaf lobes project backwards c) cut stems exude a milky latex and d) the long thin taproot – a young rosette may have a root up to 36 cm long.

Look Alikes
Habitat

In British Columbia, rush skeletonweed occurs at low elevations in the Vernon area, Crescent Valley, Kimberley, Windermere and Creston. One small outbreak occurs in the South Okanagan near Okanagan Falls. Rush skeletonweed is adapted to a wide range of conditions, particularly dry grasslands with well-drained, light-textured soils. It readily invades rangelands, pastures, roadsides, croplands and other disturbed habitats.

Impact & Risks

Without control measures, rush skeletonweed will produce a mono-culture of interconnected plants. A single plant can become an entire colony. Infestations of rush skeletonweed can reduce livestock and wildlife forage. The extensive and deep root system makes the plant difficult to manage. The latex the plant produces can cause serious problems with crop harvest machinery when the plant establishes on cropland. Rush skeletonweed can provide limited value as forage during a drought. Rosette leaves and pre-flowering stems are palatable and nutritious.

Prevention & Mitigation

 Maintain grasslands in a healthy, vigorous condition to ensure a productive plant community; competitive perennial plants utilize water and nutrients that would otherwise be readily available to rush skeletonweed.
• Regularly patrol your property for rush skeletonweed and take action immediately if skeletonweed plants are identified.
• Immediately re-vegetate disturbed soils with a suitable grass seed mixture that provides dense, early colonization to prevent weed invasion.

Treatment & Disposal

Small, isolated infestations of rush skeletonweed may be hand pulled, however repeat treatments will likely be required because of the plant’s extensive root system. The entire root of the plant should be removed to avoid regrowth. Pulling should occur before seed production, otherwise seed heads should be cut and bagged. Mowing and cultivation are ineffective at controlling rush skeletonweed.

Chemical control is also an option. Before applying herbicides, read the label for full use and precautionary instructions. Consult the most recent edition of the Alberta Agriculture and Forestry Crop Production Guide for the selection and application of chemicals to protect your crop:

Two biological control agents, Aceria chondrillae (gall mite) and Puccinia chondrillina (stem and leaf rust) have been released in BC. Both agents have shown varying success. Selective grazing with sheep has also shown to control rush skeletonweed if the weed is grazed at a moderate level and desirable plants are only grazed lightly.

Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.