Information about yellow starthistle

Yellow Starthistle (Centaurea solstitialis L.)

FamilyFamily: Compositae

Description and VariationDescription and Variation: Yellow starthistle is a member of the sunflower or daisy family, Asteraceae (Compositae). As its name indicates, it is characterized by a yellow thistle-like flower with 3/8- 3/4 inch yellowish spines in star-like arrangement at the base of the flower head. The flower heads occur singly a the ends of branched stems 18-36 inches high which arise from a basal rosette of leaves. The stem and leaves are a dull green color and covered with fine woolly hairs. The basal rosette leaves are pinnately lobed with the distal portion more rounded and larger. As leaves ascend the stem they become shorter and narrower with pointed tips. Their arrangement is alternate and the leaf bases extended down the stem producing a winged effect. The yellow starthistle flower heads consist of tubular yellow florets in a discoid head about one inch in diameter. The marginal flowers produce nonplumed seeds and the central flowers plumed seeds. The root is a taproot extending deeper than the annuals it may compete with for moisture and nutrients.

Economic ImportanceEconomic Importance: Yellow starthistle was introduced to the western United States from the Mediterranean. It was first found growing in ballast grounds of our west coast seaports. It has spread extensively throughout California and to the Pacific Northwest. Approximately 800 million acres are involved in California, 1,130,000 acres in Idaho, 4,000 acres in Oregon, and 134,000 acres in Washington. Cattle feeding on yellow starthistle may be poorly nourished and can be damaged by the spiny heads. Seeds for crops and feed become contaminated. Removal of yellow starthistle seeds increases the expense of certified seed. Recreation lands are becoming infested.

Horses may be poisoned and develop "chewing disease" or E.N.E. (Equine nigropallidal encephalomalacia) if they ingest large quantities (86 - 200 percent body weight) over one to two months. The disease is characterized by acute inability to eat or drink and the horses may die from dehydration and starvation. Only horses are affected. Chemical substances in yellow starthistle are somehow altered in the processes of digestion and metabolism producing a toxin which causes death of nerve centers in the brain controlling normal eating and drinking mechanisms. There is no cure.

Geographical DistributionGeographical Distribution: Yellow starthistle is native to Eurasia and has spread from west coast ballast areas to sea ports throughout California and the Pacific Northwest. California has about 800 million acres infested; Idaho 1,128,800 acres; Oregon 3,950 acres; Washington 133,380 acres. In California the area infested has increased more that six times since 1958.

Yellow starthistle in Washington is concentrated in the Southeast corner but extends as far north as Stevens County. In the Blue Mountains of Washington, yellow starthistle performs best in deep silt loams on south slopes. However, any semiarid or subhumid area is susceptible. Yellow starthistle is primarily a rangeland weed. Eighty-two percent of the total infested area in Washington was rangeland and 11.5 percent occurred on edge of croplands.

Contaminated seed and feed are important sources of spread. Livestock, farm equipment, and vehicles, wind, animals, birds, and man may also be responsible for the spread.

HabitatHabitat: Yellow starthistle has the ability to germinate and develop in nearly all of the semiarid to subhumid rangelands in the west. In Washington, yellow starthistle has its best performance in deep silt loams on the south slopes of the Blue Mountains. However, it also survives and forms dense infestations in shallow rocky soils with as little as ten inches precipitation. This adaptability enables it to be established on poor quality rangeland, edges of cropland, idle farmlands and pastures, roadsides, railways, and recreational areas.

HistoryHistory: Yellow starthistle is thought to have originated along the Mediterranean Coast and has spread throughout Europe as far as the Asian steppes. Yellow starthistle was first reported growing on ballast grounds near western seaports. Early California records indicate C. solstitialis at Oakland in 1869 and Vacaville in 1887. By 1965, the California Department of Food and Agriculture estimated 1.9 million acres were infested.

By the 1920's it was widely distributed in Eastern Washington. It has spread as far north as Stevens County. An outbreak in Okanogan from certified but contaminated seed occurred following seeding after a fire. Action taken by Washington State Department of Agriculture has resulted in legislation that will decrease or eliminate this problem. It is a restricted noxious weed in seed.

Growth and DevelopmentGrowth and Development: Yellow starthistle is a winter annual that begins its growth in the fall from seeds that germinate when moisture conditions improve and temperature is in the sixties. Oblong tongue shaped cotyledons or seed leaves emerge in the early spring. Secondary leaves develop forming a rosette of leaves that increase in size and number (from 5 - 25 leaves in a rosette). In late May to June, the plant begins to bolt, sending up a stalk to about 30 inches in height and whose top is a firm bud. The stalks branch and flower buds form at the end of each. In mid-July to early August bright dandelion-yellow flower heads appear. Plants begin to dry in August and become easily identifiable skeletons that are silvery gray with a white cottony flowerhead. More than 150,000 seeds per plant may be produced in a single season, and these may remain viable in the soil for several years. Seeds are of two types: plumed and plumeless. Plumed seeds are subject to dispersal by gusts of wind and may be carried for considerable distance. Plumeless seeds tend to remain in the head until it falls apart. The seeds germinate near the base of the mother plant. With the onset of late fall rains, yellow starthistle seeds begin to germinate and the cycle is repeated. However, because of varying conditions, distribution and maturation rates, and long viability, some may germinate at any time of the year.

ReproductionReproduction: Reproduction is through seed. A winter annual, yellow starthistle has an abundant seed production - 150,000 per plant per season. The seed is spread by wind, as a contaminant of commercial seeds, alfalfa, clover, hay, straw, vehicles, construction and maintenance equipment, farming equipment, motor rail vehicles, animals, man, and birds, especially finches. The seeds remain viable for years. The seeds are plumed and plumeless.

Mechanism of seed dispersalMechanism of seed dispersal: The plumed seeds, upon maturity, are thrust upward into the opening at the top of the bracts. In that position, they are subject to dispersal by gusts of wind or other disturbance which results in movement of the stem. Those seeds may germinate as soon as moisture conditions are favorable. Plumeless seeds are produced by the outer circle of florets associated with the bracts. Consequently they tend to remain in the head until it falls apart. This provides a second period and method of seed dispersal.

Response to HerbicidesResponse to Herbicides: Yellow starthistle in the rosette stage is not difficult to kill with herbicides such as 2-4-D. Plants in the flowering and seed production phase are resistant. Seeds are also resistant. Picloram not only kills the rosette stage but, due to residual action, is effective on seedlings developing in the next season. However, skipped or missed areas of herbicide application may occur. Seeds may survive beyond residual action of picloram. Resistance to picloram has been reported. Refer to Pacific Northwest Weed Control Handbook for detailed management.

Response to Cultural MethodsResponse to Cultural Methods: The primary site of yellow starthistle infestation is rangeland. Mechanical removal is economically unsound for dense infestations. However, initial infestations, such as occurred from contaminated seed mix in Okanogan County, have been lessened by hand pulling, flagging, and a herbicide pellet application. Proper grazing management, including rest and deferment to allow grasses to regain vigor, will both limit yellow starthistle invasions and improve the range's condition. In California, frequent cultivation slows or inhibits the plant, preventing it from fully exploiting cultivated grassland steppes.

Larson and McInnis (1989) report that a combination of "Tualatin" tall oatgrass or "Paiute" orchard grass with picloram application effectively controlled yellow starthistle and improved forage production.

Biocontrol PotentialsBiocontrol Potentials: Washington State initiated a yellow starthistle biological control program in 1985 with the release of a beetle Bangosternus orientalis. The beetles feed on small buds and lay eggs in medium sized buds. Larvae hatch and feed on developing seed destroying all of them within the head. Pupation occurs in the damaged heads and the emerged adults overwinter in the soil. This beetle has reduced yellow starthistle seed production by about 60 percent. Two other beetles which destroy yellow starthistle seed in affected heads are Eustenopsis villosus - released and successfully colonized at a site in Whitman County in 1990 - and Larinus curtus.

A yellow starthistle seed eating fly, Chaetorelia australis was released in 1988. Another fly with inhibiting effects on yellow starthistle is Urophora sirunaseua. Several thousand pupae of a starthistle-specific gall producing wasps have been released in Umatilla County, where they may help limit starthistle spread at base of the Blue Mountains.

ReferencesReferences:

*Burrill, L.C., R.D. William, R. Parker, C. Boerboom, R.H. Callihan, C. Eberlein, and D.W Morishita. 1992. Pacific Northwest Weed Control Handbook. Extension Services of Oregon State University, Washington State University, and the University of Idaho.

*Callihan, R.H., F.E. Northam, J.B. Johnson, E.L. Michalson, and T.S. Prather. 1989. Yellow Starthistle: Biology and Management in Pasture and Rangeland. Current Information Series No. 634. University of Idaho Cooperative Extension, Moscow, ID.

*Callihan, R.H., J.B. Johnson, and E.L. Michalson. 1987. Progress Report for Fiscal Year 1987. Yellow Starthistle Cooperative Agreement. University of Idaho, Department of Plant, Soil and Entomological Sciences, Moscow, ID.

*Callihan, R.H., R.O. Schirman, and F.E. Northam. 1990. Picloram resistance in yellow starthistle. Progess report submitted for publication in Western Society of Weed Science Annual Research Report.

*Callihan, R.H. 1990. Picloram resistance in yellow starthisle. Abstract of paper presented at 1990 annual meeting of Weed Science Society of America. Montreal, Canada.

*Carlson, J.E., D.B. Willis, E.L. Michalson, and R.H. Callihan. 1990. Yellow Starthistle in North-Central Idaho: A Survey of Fammers; and Ranchers’ Behavior and Attitiudes (1982 and 1988). Bulletin No. 712. University of Idaho, College of Agriculture, Agricultural Experiment Station, Moscow, ID.

Higgins. R.E. and Viambitsch R.L. 1978. Yellow Starthistle, a Threat to Idaho Land Users. Current Information Series #445. University of Idaho College of Agriculture, Moscow, ID.

*Larson, L.L. & McInnis M.L. 1989. Response to yellow starthistle (Centaurea solstitialis) & grass biomass to grass, picloram, and fertilizer combinations. Weed Technology 3:497-500.

*McBarron, E.J. 1983. Poisonous Plants: Handbook for Farmers & Graziers. Inkata Press, Melbourne.

*Panter, Kip E. 1991. Neurotoxicity of knapweeds in horses in noxious range weeds. In: James L.F., J.O. Evans, M.H. Ralphs, and R.D. Child, eds. Noxious Range Weeds, pp. 316-324. Westview Press, Boulder, CO.

*Piper, G. 1991. Yellow starthistle biological control efforts in Washington. Knapweed 5(2):4.

*Roche’, Jr., B.F., and C.J. Talbott. 1986. The Collection History of Centaureas found in Washington State. Research Bulletin XB 0987. Agriculture Research Center, College of Agriculture and Home Economics, Washington State University, Pullman, WA.

*Roche’ C.T. & B.F. Roche’, Jr. 1988. Distribution & amount of four knapweed (Centaurea L.) species in eastern Washington. Northwest Science 62: 242-253.

*Roche’, Jr., B.F., G.L. Piper, & C.J. Talbott. 1986. Knapweeds of Washington. EB 1393. Washington State Cooperative Extension, Pullman, WA.

Shelley, R.L. & Callihan, R.H. UI Weed Wise Yellow starthistle. P.N.W. Weed Topics 81-6.

*Smathers, R.L., R.O. Brooks, and E.L. Michalson. 1985. Controlling Yellow Starthistle: Economic Considerations. Bulletin No. 650. University of Idaho, College of Agriculture, Agricultural Experiment Station, Moscow, ID.

*Styner, Roger A. & Sours, John M. 1992 The use of commercial grasses in the control & suppresson of noxious weeds. Grassland West Co., Clarkston, WA.

*Thomsen, C.D., W.A. Williams, M.R. George, W.B. McHenry, F.L. Bell, and R.S. Knight. 1989. Managing yellow starthistle on rangeland. California Agriculture 43:4-7.

This page was last updated 03/31/07