From Medicinal Plants Usage
Template:Globalize/North America Template:Italic title Template:Taxobox Centaurea solstitialis, yellow star-thistle, is a member of the family Asteraceae, native to the Mediterranean Basin region. The plant is also known as golden starthistle, yellow cockspur and St. Barnaby's thistle (or Barnaby thistle)<ref>Template:Cite web</ref> The plant is a thorny winter annual species in the knapweed genus.
Centaurea solstitialis is an annual herb from the Asteraceae family. During the vegetative stage if forms a rosette of non-spiny leaves (5–20 cm diameter). As the summer approaches, it produces a flowering stem (1 m) which will produce numerous spinous capitula containing numerous (10-50) yellow flowers. Flowers within capitula are pollinated by insects and each capitula will produce a mix of (10-50) pappus and non-pappus seeds. It is an annual semelparous species, and will die after reproduction is completed, normally by the end of the summer.
Centaurea solstitialis is a weed also on its native European range (e.g., Turkey, Greece, Italy, France, Spain), consequently, it inhabits highly disturbed ruderal habitats, being typically found on roadsides and cereal crop margins. After introduction in several parts of the world as an exotic species (e.g., Australia, Argentina, Chile, USA),<ref name="gbif.org">http://www.gbif.org</ref> it has developed local adaptations to the different habitats colonized,<ref>Hierro, J. L., Eren, Ö., Khetsuriani, L., Diaconu, A., Török, K., Montesinos, D., … Callaway, R. M. (2009). Germination responses of an invasive species in native and non-native ranges. Oikos, 118(4), 529–538. doi:10.1111/j.1600-0706.2009.17283.x</ref><ref>Graebner, R. C., Callaway, R. M., & Montesinos, D. (2012). Invasive species grows faster, competes better, and shows greater evolution toward increased seed size and growth than exotic non-invasive congeners. Plant Ecology, 213(4), 545–553. doi:10.1007/s11258-012-0020-x</ref> and an incipient level of reproductive isolation between native and non-native ranges has been detected.<ref>Montesinos, D., Santiago, G., & Callaway, R. M. (2012). Neo-allopatry and rapid reproductive isolation. The American Naturalist, 180(4), 529–33. doi:10.1086/667585</ref> This makes this species a candidate case for incipient ecological speciation.
Centaurea solstitialis grows as a balanced part of the ecosystems in Eurasia, where it is kept in check by an assortment of natural herbivore enemies and other plants that have co-evolved with it in its native habitat. However, it has been introduced in several parts of the world, including Australia, Argentina, Chile, and the USA.<ref name="gbif.org"/> In many of these non-native regions, where the particular array of natural biological controls found in the native regions do not exist, it has become an invasive species and noxious weed.
The Yellow star-thistle plant has the ability to create monotypic stands and habitats in the cultivated soil of fields, graded dirt sites, and disturbed natural ecosystem lands. Its colonization eliminates and prevents other plant species from growing, terminating the habitat's biodiversity. Extensive spreading monotypic fields of yellow starthistle are not uncommon. Its growth plasticity, competitiveness, preference for the Mediterranean climate, and a lack of natural herbivore enemies and co-evolved species, make it a very successful invader. The plant is an invasive pest in field crops, degrades native plant habitats and natural ecosystems, prevents the grazing of domestic animals in rangelands, and is a physical barrier to indigenous animal movement in wildlands.<ref>Yellow Starthistle species profile from the U.S. Department of Agriculture National Invasive Species Information Center</ref>
Star thistle is a valuable source of pollen, thus nectar for pollinators. Yellow star thistle, a noted pest plant, is a major nectar source for many central valley and foothill butterflies.<ref>http://www.patternliteracy.com/644-saving-native-wildlife-with-invasive-plants</ref> Star Thistle populates ground that has been abused: dry, compacted, or scraped clean. A plant with a tap root system, it has a crucial role in restoring the soil by bringing up vital micronutrients. Similar to many plants classified as 'weeds', they "quickly establish in, protect, and restore soil that has been left exposed by natural and human-caused disturbances". <ref>http://www.extension.org/pages/18529/an-ecological-understanding-of-weeds#.VXnl8M7BLGk</ref>
The introduction of Centaurea solstitialis in North America probably occurred in California sometime after the start of the California Gold Rush, as a fodder seed contaminant in imported Chilean-harvested alfalfa seed, also known as Chilean clover (Trifolium macraei).<ref name="ucd"/> Introduction in other parts of the world is poorly known.
In California, Yellow star-thistle was dispersed into agricultural fields, and immediately took hold in the state's Mediterranean-type climate areas. Human factors, such as mowing, land grading for development and roads, domestic animal grazing, and disturbance of the soil surface for agricultural tillage and wildland firebreaks have and continue to contribute to the successful thriving and spread of this plant. Yellow starthistle is now a very common sight in vacant lots and fields, along roadsides and trails,in pastures and ranch lands, and in parks, open-space preserves and natural areas.
After the turn of the 20th century, Spain, France, Italy, and perhaps Turkestan were also likely sources of the invasion's seed in California.<ref name="ucd" /> Since its introduction to California in the mid-nineteenth century,<ref name="ucd">Yellow Starthistle Information from a University of California, Davis (UCD) website</ref> it has become a large-scale invasive species (noxious weed or invasive exotic) throughout twenty-three states. It currently dominates over Template:Convert in California alone.<ref>Template:PDFlink, Mount Diablo Interpretive Association. Retrieved on 2008-10-15.</ref><ref name="wric.ucdavis.edu">1970 UCD Yellow Starthistle Information website - Map of Distribution of yellow star-thistle in the U.S. Template:Wayback</ref>
By 1970,<ref name="wric.ucdavis.edu"/> yellow star-thistle had reached 23 U.S. states.<ref name="ucd" /> According to the USDA Forest Service, as of 2006 the plant has been reported present in 41 of the 48 contiguous U.S. states, with the only exceptions being Maine, Vermont, and five of the Deep South states (Arkansas, Louisiana, Mississippi, Alabama, and Georgia).<ref name="USFS">Template:PDFlink, USDA Forest Service. Retrieved on 2008-10-15.</ref> The plant is considered an invasive species in six of the 41 states: California, Oregon, Washington, Idaho, Utah, and New Jersey.
Most herbicides used for controlling Yellow Star-thistle are registered for range lands, right-of-way, and other non-crop areas. Many auxin-like or growth-regulator herbicides are used for post-emergence control, including 2,4-D, aminopyralid, clopyralid, dicamba, picloram and triclopyr. Alternatively, glyphosate (e.g., Monsanto "Roundup") may be used. Pre-emergence herbicides used for yellow star-thistle control include chlorsulfuron and sulfometuron. Pre-emergence and post-emergence herbicides may be used effectively together to kill growing plants as well as any new seedlings that may emerge from the copious soil seed bank often produced by yellow starthistle. Controlled burning may also be used in conjunction with clopyralid application as an effective integrated approach to yellow star-thistle management.<ref>Template:Cite web</ref>
A yellow star-thistle biotype resistant to picloram was discovered in a pasture near Dayton, Ohio in 1988. This biotype was determined to have cross resistance to other auxin-like herbicides, especially clopyralid.<ref>Fuerst E.P., Sterling T.M., Norman M.A., Prather T.S., Irzyk G.P., Wu Y., Lownds N.K., and Callihan R.H., 1996. Physiological characterization of picloram resistance in yellow star-thistle. Pest Biochem Physiol 56:149–161.</ref> Resistance was discovered to be conveyed by a single nuclear recessive gene.<ref>Sabba R.P., Ray I.M., Lownds N. and Sterling T.N., 2003. Inheritance of resistance to clopyralid and picloram in yellow star-thistle (Centaurea solstitialis L.) is controlled by a single nuclear recessive gene. J. Heredity 94(6): 523-527.</ref>
Yellow star-thistle is sometimes resistant to removal methods such as mowing and burning, because of its long root system and the seeds' ability to withstand fire. The plant has been the target of biological pest control programs with positive results. Seven types of seed-feeding insects have been released (one accidentally) to control the plant.<ref>Template:Cite web</ref><ref>Pitcairn, M. J., B.Villegas, D. M. Woods, R. Yacoub, and D. B. Joley. 2008. Evaluating implementation success for seven seed head insects on Centaurea solstitialis in California, USA, pp. 610-616. In M. H. Julien, R. Sforza, M. C. Bon, H. C. Evans, P. E. Hatcher, H. L. Hinz, and B. G. Rector (eds.), Proceedings of the XII International Symposium on Biological Control of Weeds. La Grande Motte, Montpellier, France (in press).</ref>
- Three species of weevil in the beetle subfamily Cleoninae effectively reduce seed production in the yellow star-thistle.
- Yellow star-thistle bud weevil (Bangasternus orientalis) is a fuzzy brown weevil that lays its eggs in the flowers, and when its larvae hatch, they feed on the developing seed.<ref>Campobasso, G.; Sobhian, R.; Knutson, L.; Terragitti, G. 1998. Host specificity of
Bangasternus orientalis Capiomont (Coleoptera: Curculionidae) introduced into the United States for biological control of yellow starthistle (Centaurea solstitialis L., Asteraceae: Carduae). Environmental entomology,. v. 27 (6), p. 1525-1530.</ref>
- Yellow starthistle hairy weevil (Eustenopus villosus) is a long-snouted, hairy-looking weevil that lays a single egg inside each flower bud. The larva then consumes the seeds within.<ref>Fornasari, L., and R. Sobhain. 1993. Life history of Eustenopus villosus (Coleoptera’ Curculionidae), a promising biological control agent for yellow
starthistle. Environ. Entomol. 22: 684-692.</ref><ref>Connett, J.F.; Wilson, L.M.; McCaffrey, J.P.; Harmon, B.L. 2001. Phenological synchrony of Eustenopus villosus (Coleoptera: Curculionidae) with Centaurea solstitialis in Idaho. Environmental entomology, v. 30 (2), p. 439-442.</ref>
- Yellow star-thistle flower weevil (Larinus curtus) is a brownish weevil that lays eggs in the flowers as it feeds on the pollen. The larvae then eat the seeds when they hatch.<ref>Fornasari, L. and C.E. Turner. 1992. Host specificity of the Paleartic weevil Larinus curtus Hochut (Coleoptera: Curculionidae), a natural enemy of Centaurea solstitialis L. (Asteraceae: Cardueae). In: Proceedings of the Eighth International Symposium on Biological Control of Weeds. 2–7 February 1992. Lincoln
University, Canter- 1bury, New Zealand, 385-391</ref> This insect has failed to established dense populations in the United States.<ref>Pitcairn, M. J., G. L. Piper, and E. M. Coombs. 2004. Yellow starthistle, pp. 421-435. In E. M. Coombs, J. K. Clark, G. L. Piper, and A. F. Cofrancesco, Jr. (eds.), Biological control of invasive plants in the United States. Oregon State University Press, Corvallis, OR</ref><ref>Pitcairn, M. J., D. M. Woods, and V. Popescu. 2005. Update on the long-term monitoring of the combined impact of biological control insects on yellow starthistle, pp. 27-30. In D. M. Woods (ed.), Biological control program annual summary, 2004. California Department of Food and Agriculture, Plant Health and Pest Prevention Services, Sacramento, CA</ref>
- Four species of tephritid fruit fly also attack the seedheads of yellow star-thistle.
- Yellow star-thistle peacock fly and false peacock fly (Chaetorellia australis and Chaetorellia succinea, respectively, the latter released unintentionally) are small nectar-feeding flies that deposit eggs into the seedheads, where their larvae consume the seeds and flower ovaries.<ref>Turner, C.E., G.L. Piper and E.M. Coombs. 1996. Chaetorellia australis (Diptera: Tephritidae) for biological control of yellow starthistle, Centaurea solstitialis (Compositae), in the western USA: establishment and seed destruction. Bull. Entomol. Res. 86: 1 77-182.</ref>
- Banded yellow star-thistle gall fly (Urophora sirunaseva) produces larvae that pupate within a woody gall within the flower and disrupt seed production.<ref>Sobhian, R. 1993. Life history and host specificity of Urophora sirunaseva
(Herng)(Dipt., Tephritidae), an agent for biological control of yellow starthistle, with remarks on the host plant. J. Appl. Entomol. 116: 381-390.</ref>
- Another gall fly Urophora jaculata was released in 1969 but never established.<ref>Turner, C.E., Johnson, J.B., McCaffrey, J.P., 1994. Yellow starthistle, Centaurea solstitialis L. (Asteraceae). In: Nechols, J.R. (Ed.),
Biological Control in the U.S. Western Region: Accomplishments and Benefits of Regional Research Project W-84 (1964-1989). Division of Agriculture and Natural Research, University of California, Berkeley, pp. 274–279</ref>
A variety of the rust fungus Puccinia jaceae var. solstitialis, first released in July 2003 on a ranch in the Napa Valley, has shown promise as an agent against yellow star-thistle.<ref>Fungus Unleashed To Combat Yellow Star-thistle from the U.S. Department of Agriculture website</ref> The rust causes widespread pathology in the leaves of the plant and slow its dispersal. The fungus Synchytrium solstitiale (Synchytrium of phylum Chytridiomycota) is also being considered as an agent of biological control. <ref name=Gleason> Voigt K., A.V. Marano, & F.H. Gleason. 2013. Ecological & Economical Importance of Parasitic Zoosporic True Fungi. in: The Mycota: A Comprehensive Treatise on Fungi as Experimental Systems for Basic & Applied Research Vol. 11 Agricultural Applications. 2nd edition Eds: K. Esser & F. Kempken. Springer: New York pg.243-270. </ref>
California researchers (Thomsen et al., 1996) tested mowing in combination with controlled sheep grazing and subterranean clover plantings for starthistle control. The researchers theorized that the subclover would help fill the niche vacated by the yellow starthistle populations.
They compared subclover seeding + grazing + two mowings - grazing + mowing without subclover - and an untreated area without grazing, subclover, or mowing. Thistle seed production was 130 times higher where only one mowing was done, and 1,720 times higher where nothing was done, as compared to the area that had been grazed and mowed twice. This study shows that excellent yellow starthistle control can be achieved with competition from desirable plants, such as subclover, combined with mowing and rotational grazing.<ref>http://www.groworganic.com/organic-gardening/articles/natural-control-of-yellow-star-thistle</ref>
Although these biocontrol agents have proven somewhat effective at controlling Centaurea solstitialis, there is interest in finding additional agents to further control the species. Two weevils, including Larinus filiformis, a flowerhead feeding weevil, and Ceratapion basicorne (Illiger) (Coleoptera: Apionidae), which develops in the root crown of rosettes have been evaluated and proposed for introduction.<ref>Smith, L. 2007. Physiological host range of Ceratapion basicorne, a prospective biological control agent of Centaurea solstitialis (Asteraceae). Biol. Control 41: 120-133.</ref> Also under evaluation are a stem-feeding flea beetle Psylliodes chalcomera (Illiger) (Coleoptera: Chrysomelidae) (Cristofaro et al. 2004a), a lacebug Tingis grisea Germar (Heteroptera: Tingidae), and a mite Aceria solstitialis de Lillo (Acari: Eriophyidae). (de Lillo et al. 2003).<ref>Smith, L. 2004. Prospective new agents for biological control of yellow starthistle, pp. 136-138. Proceedings 56th Annual California Weed Science Society, 12–14 January 2004, Sacramento, CA</ref>
Species similar to Centaurea solstitialis are purple star-thistle (Centaurea calcitrapa), sulphur star-thistle (Centaurea sulphurea), Maltese star-thistle (Centaurea melitensis), and rough star-thistle (Centaurea aspera).<ref name="The Wild Flower Key">Template:Cite book</ref>
- USDA - " Larinus filiformis as a Biological control agent for Centaurea solstitialis (flowerhead feeding weevil)
- Balciunas, J. K., and B. Villegas; "Unintentionally released Chaetorellia succinea (Diptera: Tephritidae): Is this natural enemy of yellow starthistle a threat to safflower growers?"; Environ. Entomol 30: 953-963; pub. 2001.
- Species Profile--Yellow Star Thistle (Centaurea solstitialis), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Yellow Star Thistle.
- USDA Profile - Centaurea solstitialis (yellow star-thistle)
- U.C. Jepson Manual treatment - Centaurea solstitialis
- California Integrated Pest Control - Biocontrol of Centaurea solstitialis -Yellow star-thistle
- Centaurea solstitialis - U.C. CalPhoto gallery
- Texas AgriLife Extension - Toxic Plants of Texas - Starthistles - Yellow Starthistle is toxic to horses
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