Rush Skeletonweed

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Rush Skeletonweed Eradication Project: Rush skeletonweed (Chondrilla Juncea) is an A-rated weed of moderate distribution in Fresno. Rush skeletonweed is a non-native invasive noxious weed species from southern Europe that was introduced into San Luis Obispo County in 1965. The earliest known find in Fresno County was in July, 1981. Rush skeletonweed was found in an alley in downtown Fresno near the railroad tracks. Subsequent finds in the 1990’s were west of downtown Fresno in a residential area. An eradication project began in 1997. Currently rush skeletonweed is being found in the southeastern portion of Fresno City and southeastward into urban and agricultural areas of Fresno County. It continues to spread southeastwardly. Recent finds are within 15 miles of the entrance to Sequoia National Forest on Highway 180.

Rush skeletonweed can be a serious agricultural pest through the reduction of crop yield and the choking of harvesting machinery. Due to its limited distribution and its ability to rapidly spread, delimitation surveys and treatment to eradicate this weed is critical. Each skeletonweed plant can produce up to 20,000 seeds and be carried by wind, vehicles, clothing and animals. Once skeletonweed is established it produces a very extensive and deep root. Control methods for rush skeletonweed include chemical spraying and repetitive plowing.


Mature Rush Skeletonweed

Rush Skeletonweed Flowers and Seed Heads

Rush skeletonweed grows to be 1 to 4 feet tall. It is a perennial. The lower 4 to 6 inches of the stem have downward bent red hairs. Milky juice is exuded when the leaves are torn. The flowers are yellow with flat strap-shaped petals with distinct lobes. In the Fresno area flowering is usually June through the first frost. It will infest well-drained light-textured disturbed soils. Infestations are found along roadsides, in rangelands, grain fields, vineyards, orchards and pastures. The small leaves and the rigid, wiry stems make herbicide control difficult. The root system is extensive and deep. Rush skeletonweed can reproduce vegetatively from adventitious buds in the roots. Plowing just once can be problematic, as the roots are broken into small pieces they can develop into new plants.

Due to the elimination of the weed control program at the State level Fresno County Department of Agriculture staff will perform minimal surveys of rush skeletonweed. Department of Agriculture staff will begin a limited survey and treatment program for rush skeletonweed in May of each year. The project may continue through October.