Photographer: Charles Turner Affiliation: USDA Agricultural Research Service Source: Bugwood.org Copyright: (CC BY 3.0).
Yellow starthistle (Centaurea solstitialis) is an invasive weed that can reach of height of 2 to 6 feet tall with a deep taproot. Leaves are 2 to 3 inches long except for the top half of the plant where the leaves are only 0.5 to 1 inch long. The plant has a white appearance due to a cottony covering of the leaves and stem. The blooms are similar to a dandelion with a yellow color and sharp spines protruding outward.
There is no value of the yellow starthistle for livestock and it can be detrimental if eaten by horses. The yellow starthistle is known to cause chewing disease in horses and can be fatal if symptoms persist and the animal is untreated. Horses are the only known animal to be effected by yellow starthistle. Native plants are affected by yellow starthistle due to growth in high densities preventing other plant species to inhabit the same area.
The yellow starthistle has a high reproductive potential with up to 300,000 seeds released within a square meter resulting in 95% viability following dispersal. Seeds will germinate within a calendar year, but if environmental conditions are unfavorable the seed can remain dormant and viable for up to 3 years. Following germination, energy is spent on root formation that average 3 feet in length. The ability to grow deep roots allows the yellow starthistle to survive during dry summer months and out compete native shallow rooted plants.
First introduced to the United States in 1850 in California, the yellow starthistle, though native to Eurasia, was transferred from South America. The plant was introduced accidentally through contaminated seed.
Native Origin: Mediterranean region of Europe
Habitat: The yellow starthistle can grow in a variety of habitats and soil compositions. It may be found around rangeland, cropland, roadsides, and railways.
U.S. Present: Marjority of United States - View map provided by EDDMapS, 2012
Texas: Central and north Texas in the Blackland Prairies, Cross Timbers and Prairies, and Edwards Plateau.
The yellow starthistle is difficult to eradicate and effective treatment requires application periods of longer than a year. Current populations must be controlled and new seed germination prevented to successfully remove this plant. Prevention is key to controlling the yellow starthistle from becoming established in new areas by scanning roadsides for new plants and removing them. Grass seeds should be inspected and purchased from reliable sources to prevent any contamination of yellow starthistle. Grazing or mowing can be an effective management technique if used aggressively. Burning is successful if done at the end of the rainy season when flowers are first appearing on the yellow starthistle.
Czarapata, Elizabeth J. 2005. Invasive Plants of the Upper Midwest, An Illustrated Guide to their Identification and Control p. 134
DiTomaso, Joseph M., Guy B. Kyser, and Marla S. Hastings. 1999. Prescribed burning for control of yellow starthistle (Centaurea solstitialis) and enhanced native plant diversity. Weed Science 47(2): 233-242.
Gelbard, J. L., & Harrison, S. 2005. Invasibility of roadless grasslands: an experimental study of yellow starthistle. Ecological Applications, 15(5), 1570-1580.
EDDMapS. 2012. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health.
Maddox, Donald M., and Aubrey Mayfield. 1985. Yellow starthistle infestations are on the increase. California Agriculture 10-12.
Roche Jr., B.F., C.T. Roche, and R.C. Chapman. 1994. Impacts of grassland habitat on yellow starthistle (Centaurea solstitialis L.) invasion. Northwest Science 68(2): 86-96.