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Scientific Name:

Common Name:

Xanthium spinosum L.
Spiny cocklebur
Family: Asteraceae

USDA Plant Code: XASP2

Habitat: Rowcrop, fields, waste areas

Growth Habit: Annual Forb/herb

Native Environment: South America

Introduction



Spiny Cocklebur Plant
Problems Caused
Spiny cocklebur is an annual plant found in highly disturbed habitats and farm areas. The burs (fruits) of this species become tangled in the fur of livestock, increasing costs to the consumers of wool products. It competes with crops and is a nuisance when growing with hand-harvested crops. The seeds and seedlings of spiny cocklebur are poisonous if consumed, and they are particularly toxic to swine and horses.

Regulations
Spiny cocklebur is listed as a “B” designated quarantine weed in Oregon and a class “C” noxious weed in Washington. In Arkansas, the genus Xanthium is listed as noxious weeds, likely more for spiny cocklebur’s congener Xanthium strumarium (rough cocklebur), which has a much wider distribution in the state.

Description


Vegetative Growth
Spiny cocklebur is an annual plant that blooms in summer. It grows to 5 feet tall with striate stems that are yellowish or brownish gray. The leaves may be entire or toothed or lobed. The lower surface of the leaves is covered with white hairs, and the upper leaf surface is white-veined. Leaves are 1-3 inches long and have a 3-forked spine at the leaf base, giving this species the common name “spiny” cocklebur.



Spiny Cocklebur Flower
Flowering
Male and female flowers are separated, but they occur on the same plant. Male flowers form above the female flowers in the axils of the uppermost leaves. Female flowers occur in the leaf axils lower on the plants. As the fruit develops from the female flowers, the bur that bears a beak and hooked bristles begins to develop. On average, plants produce 150 burs, each containing two seeds.

Dispersal
A primary dispersal mechanism for spiny cocklebur is “hitchhiking” on animal fur or human clothing. The fruits float in water, and can also be effectively dispersed by water. Seeds can be spread by clinging to feedsacks or in contaminated hay. Ungerminated seeds remain viable for several years in the soil.

Spread By
Spiny cocklebur is spread by livestock and the transport of livestock from infested fields to uninfested fields.

Habitat


Spiny cocklebur is found in open and disturbed waste places. It can be found growing along roads, barnyards, pastures, vacant lots, and other disturbed sites. It also can be common around moist disturbed sites such as along ditches, canals, river terraces, and floodplains.

Distribution


United States
Spiny cocklebur is native to South America, but now is found throughout the contiguous U.S., though it is not recorded from Arkansas, Louisiana, Minnesota, North Dakota, Oklahoma, South Dakota, Vermont, Wisconsin, or Wyoming.

MidSouth
Spiny cocklebur is not a widespread pest in the MidSouth. It has not been recorded from Arkansas or Louisiana, and it is only known from one county each in Mississippi, Tennessee, and Alabama.

IPAMS Surveys:

Control Methods


Biological
There are no approved biological control agents for this species.

Chemical Control Options for Spiny Cocklebur
Herbicide Foliar spray, Broadcast
Rate per acre
2,4-D 1 to 2 quarts
2,4-DB 0.8 to 1 pint
glyphosate 2 to 4 quarts
triclopyr 3 to 4 pints
imazaquin 1.8 to 2.4 ounces
imazapyr 3 to 4 pints
Chemical
Spiny cocklbur is susceptible to a variety of herbicides that are commonly used for broad-leaved weed control. Several auxin mimicking herbicides can be used such as 2,4-D at a rate of 1 to 2 quarts per acre, triclopyr at a rate of 3 to 4 pints per acre, and 2,4-DB at 0.8 to 1 pint per acre. The use of an auxin mimicking herbicide may be more selective for grass species than other herbicide options. Glyphosate is effective at rates of 2 to 4 quarts per acre. Imazapyr can be applied at a rate of 3 to 4 pints per acre, and imazaquin can be applied at 1.8 to 2.4 ounces per acre for spiny cocklebur control. The use of glyphosate, imazapyr, and imazaquin will typically result in non-target plant injury. Herbicide spray solutions should contain an appropriate surfactant to ensure complete leaf wetting. Herbicide applications should be made to young 3 to 5 leaf plants during active growth to maximize treatment efficacy.

Mechanical
Plants can be hand pulled before burs form; however, after the formation of burs plants should be burned to destroy the seeds. Even unripe seeds can mature on cut or pulled plants. Mowing can be effective, but as with hand pulling, mowing should be carried out before burs are formed. Burning would be effective at removing standing plants and killing seeds; however, this method is rarely used in controlling spiny cocklebur.

Physical
No physical controls are currently recommended for Spiny cocklbur.

References


Arkansas State Plant Board. 1997, revised 2006. Regulations on Plant Diseases and Pests. Circular 11, Final Rule. Online resource at http://www.plantboard.org/plant_pdfs/plantdiseasereg.pdf accessed [26 February 2009].

Oregon Department of Agriculture. 2007. State noxious weed list and quarantine. Online resource at http://www.oregon.gov/ODA/PLANT/WEEDS/lists.shtml#Noxious_weed_policy___list accessed [26 February 2009].

Pitcher, D. 1989. The Nature Conservancy element stewardship abstract for Xanthium spinosum. The Nature Conservancy, Arlington, VA. Online resource at http://tncinvasives.ucdavis.edu/esadocs/documnts/xantspi.pdf accessed [26 February 2009].

USDA, NRCS. 2009. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA. Online resource at http://plants.usda.gov accessed [26 February 2009].

Washington State Legislature. 2008. State noxious weed list and schedule of monetary penalties. Online resource at http://apps.leg.wa.gov/WAC/default.aspx?cite=16-750 accessed [26 February 2009].

More Information


Alien Plant Database
http://www.bugwood.org

Southeast Exotic Plant Pest Council
http://www.se-eppc.org

Southern Weed Science Society
http://www.weedscience.msstate.edu/swss

USDA NRCS PLANTS Database
http://plants.usda.gov/

Contributing Authors


Dr. John D. Madsen, Geosystems Research Institute, Mississippi State University
Ryan M. Wersal, Geosystems Research Institute, Mississippi State University
Dr. Travis D. Marsico, Biological Sciences, Arkansas State University

Contact Info


Dr. Gary N. Ervin
Mississippi State University
Department of Biological Sciences
Box 9627
Mississippi State, MS 39762-9627
Ph. (662)325-1203
gervin@biology.msstate.edu

Geosystems Research Institute
Contact: John D. Madsen, Ph.D.  •  WebMaster