Rush Skeletonweed

Chondrilla juncea

WA B desig. Asteraceae
Data Maturity Baseline

Washington State Classification

Class B — Control Required (Designated)

Rush skeletonweed is a threat to irrigated lands, wheat areas and rangelands.

Required control in Region 1 (all western Washington counties)

Quick Reference

Type
perennial herb
Origin
Europe, Asia and Northern Africa

Identification

Growth Habit

It is a perennial ranging in size from 1 to 5 feet tall. Its long slender taproot can grow up to 7 feet deep. Plants begin as a basal rosette of leaves and then grow 1 to 6 branching flowering stems. Plants will exude a latex sap from injured surfaces.

Leaves

Basal leaves are lobed with lobes pointing back towards the leaf base. Leaves on branching stems are few, narrow and may have entire (smooth) edges.

Flowers

Flowerheads 1/2 inch in diameter and grow in leaf axils and stem tips, single or in clusters. Flowerheads have usually 11 (7 – 15) yellow ray flowers. Green bracts at base of flower head in a single row followed by a single row of smaller bracts.

Fruit & Seeds

Seeds 0.1 inch (3 mm) with ribbed surface and white bristles (pappus) on one end that aid with wind dispersal.

Impact

Rush skeletonweed is a threat to irrigated lands, wheat areas and rangelands. Rangeland infestations displace native and beneficial forage species grazed by livestock and wildlife.

Ecology & Spread

Habitat

Rush skeletonweed is found in pastures, rangeland, cropland, roadsides, open and disturbed areas. Please click here to see a county level distribution map of rush skeletonweed in Washington.

Spread Mechanisms

seed vegetative fragments

Reproduction

Plants spread by seed with each mature plant producing between 1,500 and 20,000 seeds. Rush skeletonweed also spreads by shoot buds found along lateral roots and from shoot buds found near the top of the main root. It also grows from root fragments in the soil.

Regional Notes — Puget Sound

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Control Methods

Mechanical

  • Hand-pulling can work for small infestations. Areas must be controlled 2 to 3 times per year for 6 to 10 years to remove seedlings and re-sprouting roots. Removal of deep tap roots is easiest when soils are damp. Mowing plants repeatedly may reduce plants' biomass and seed production but may not provide eradication.

Biological Control

  • The rush skeletonweed gall midge (Cystiphora schmidti), the rush skeletonweed gall mite (Eriophyes chondrillae), and the rush skeletonweed rust fungus (Puccinia chondrillina) are biological control agents used in Washington. Contact the WSU Integrated Weed Control Project for more information.