Yellow Starthistle Centaurea solstitialis L.

Common Names:Golden star thistle, St. Barnaby’s thistle,

yellow centaury, yellow cockspur and geeldissel

What is Yellow Star Thistle?

Yellow star thistle is an annual dicot with several erect branches that each contain a flowering head covered in thorny bracts.

What is Yellow Star Thistle?

Classification:

Kingdom Plantae – Plants Subkingdom Tracheobionta – Vascular plants Superdivision Spermatophyta – Seed plants Division Magnoliophyta – Flowering plants Class Magnoliopsida – Dicotyledons Subclass Asteridae Order Asterales Family Asteraceae – Aster (Sunflower) family Genus Centaurea L. – knapweed Species Centaurea solstitialis L. – yellow star-thistle

Why is it Bad?

The thorns on the head of the star thistle interfere with livestock grazing, recreation and wildlife management

Yellow Star Thistle is also toxic to horses and can cause a potentially fatal disorder called “chewing disease.”

Reduction of biodiversity due to displacement of native vegetation.

Linda M. Wilson, Cynthia Jette, John Connett, Joseph P. McCaffrey. 2003. Biology and Biological Control of Yellow Starthistle. USDA Forest Service FHTET-1998-17 2nd Ed.

Why is it Bad?

Life History- Yellow Star Thistle

Seed germination in the fall and development into overwintering rosettes.

Rapid growth in late spring with stalk growth each with a flower bud.

Yellow flowers bloom in early summer.By late summer the plant begins to dry.

Life History- Yellow Star Thistle

Seeds dipersed by wind, water or by clinging to fur or clothing during the late summer and early fall.

Yellow star thistle continues to dry over winter and eventually loses its thorny bracts and dies.

Native Land & U.S. Introduction

Yellow star thistle is native to Eurasia.

Introduced to the U.S. in the 1800s through accidentally contaminated seeds.

U.S. Distribution

States where C. solstitialis is Listed as Invasive

• California, Idaho, Oregon, Utah, Washington, Arizona, Colorado, Montana, New Mexico, Nevada, North Dakota and South Dakota.

Control

• GrazingCattle, sheep and goats will graze on yellow star

thistle until it develops thorns.Toxic to horses.Low nutritional value Cattle with high yellow star thistle diet lose

weight. (Callihan and others 1982)

Control

• MechanicalManual removal- Effective on small patches before seed production.

Tillage- Can quickly reduce yellow star thistle seed bank, but can do the same to desirable species.Mowing- Too early or too late can increase the yellow star thistle infestation.

Too early- Mowing can remove early competition by natives.Too late- Mowing can scatter yellow star thistle seeds.

Control

• Fire ControlPrescribed burns are not effective.Fire will kill the plant but not the seeds and may

stimulate seed growthYellow star thistle thrives in areas with

increased sunlight, soil surface, bare soil and decreased competition.

Control

• ChemicalPicloram is the most widely used in the western states.

Not registered for use in California.Clopyralid is effective for control and least damaging to grasses.

Control

• Chemical cont.Picloram resistance observed in yellow star thistle in frequently treated areas.Most effective when used on early growth.It is important to incorporate other modes of

control.

Biological Control- Weevils

Bangasternus orientalis (seedhead weevil)- attacks the early bud stages

Eustenopus villosus (hairy weevil)- Feeds on mid- stage buds and lays eggs in late-stage buds

Larinus curtus (flower weevil)- Lays eggs in open flowers

Case Study

Biological Control- Flies

Chaetorellia australis (peacock fly)and C. succinea (false peacock fly)- feeds on seedheads

Urophora siruneseva(seadhead fly)- Forms galls in seedheads

C. Succinea- accidentally released and not approved due to damage to safflower.

Costs

• EcologicalDense populations of yellow star thistle use deep soil water earlier than natives.Natives can experience drought conditions in years with normal rainfall.(Benefield et. al., 2001) and (Gerlach et. al., 1998.)

Costs

• EconomicInterference with:

Livestock grazingForage harvesting proceduresLower yield and forage quality

Is it Good?

• HoneyAn important honey source in California and other western states

• MedicineUsed in Turkish folk medicine for ulcer treatment.Lab tests of flower extract show significant antiulcerogenic activity in rats.

Questions

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ReferencesBenefield, Carri B.; DiTomaso, Joseph M.; Kyser, Guy B. 1998. Impacts of yellow starthistle density

on the soil moisture profile and rangeland management. Proceedings, Western Society of Weed Science. 51: 66. [40408]

Bussan, Alvin J.; Dyer, William E. 1999. Herbicides and rangeland. In: Sheley, Roger L.; Petroff, Janet K., eds. Biology and management of noxious rangeland weeds. Corvallis, OR: Oregon State University Press: 116-132. [35716]

Carlson, John E.; Willis, David B.; Michalson, Edgar L.; Callihan, Robert H. 1990. Yellow starthistle in north-central Idaho: a survey of farmers' and ranchers' behavior and attitudes. Bulletin No. 712. Moscow, ID: University of Idaho, College of Agriculture, Agricultural Experiment Station. 11 p. [40405]

DiTomaso, Joe. 2001. Element stewardship abstract: Centaurea solstitialis L. In: Weeds on the web: The Nature Conservancy wildland invasive species program, [Online]. Available: http://tncweeds.ucdavis.edu/esadocs/documnts/centsols.html [2001, December 19]. [40416]

Gerlach, John; Dyer, Andrew; Rice, Kevin. 1998. Grassland and foothill woodland ecosystems of the Central Valley. Fremontia. 26(4): 39-43. [40400]

ReferencesHastings, Marla S.; DiTomaso, Joseph M. 1996. Fire controls yellow starthistle in California

grasslands. Restoration and Management Notes. 14(2): 124-128. [40398]Linda M. Wilson, Cynthia Jette, John Connett, Joseph P. McCaffrey. 2003. Biology and Biological

Control of Yellow Starthistle. USDA Forest Service FHTET-1998-17 2nd Ed.Maddox, Donald M.; Mayfield, Aubrey; Poritz, Noah H. 1985. Distribution of yellow starthistle

(Centaurea solstitialis) and Russian knapweed (Centaurea repens). Weed Science. 33: 315-327. [23467]

Yesilada, Erdem; Sezik, Ekrem; Fujita, Tetsuro; [and others]. 1993. Screening of some Turkish medicinal plants for their antiulcerogenic activities. Phytotherapy Research. 7(3): 263-265. [28718]

Zouhar, Kris. 2002. Centaurea solstitialis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [ 2008, December 8].