HPIPM:Cocklebur

Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Asteranae
Order	Asterales
Family	Asteraceae
Subfamily	Asteroideae
Tribe	Heliantheae
Genus	Xanthium

Scientific Name

Xanthium strumarium

Scientific Name Synonyms

Xanthium strumarium var. strumarium

Common Name

common cocklebur

Cocklebur (Xanthium strumarium)

Compiled by Steve Lackman, Montana State University, Yellowstone County Extension

and Marjolein Schat, Montana State University from the following sources:

http://plants.usda.gov/java/profile?symbol=XAST

http://www.ppws.vt.edu/scott/weed_id/xanst.htm

http://www.library.uiuc.edu/vex/toxic/cklburs/cklburs.htm

http://www.omafra.gov.on.ca/english/crops/facts/01-005.htm

http://www.agron.iastate.edu/~weeds/WeedBiolLibrary/u4cockle1.html

http://tncinvasives.ucdavis.edu/esadocs/documnts/xantstr.pdf

http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Xanthium+strumarium

http://biology.mcgill.ca/faculty/lechowicz/articles/CJPS-1982.pdf

Uchytil, Ronald J. 1992. Xanthium strumarium. 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/plants/forb/xanstr/all.html [2008, October].

Identification and Life Cycle

Cocklebur (xanthium strumarium) is an annual in the aster family (Asteraceae). Other common names include common cocklebur, and rough cocklebur. The stem below the cotyledons (hypocotyl) is purple at the base and often green in the upper portion. Cotyledons are linear to oblong in outline, waxy, smooth, fleshy, thick, approximately 3/4 to1 3/4 inches long and usually no more than 1/2 inch wide. The first true leaves are opposite, while all subsequent leaves are alternate. Leaves are triangular to ovate in outline, have stiff hairs, and are approximately 2 to 6 inches long. Leaves are irregularly lobed with leaf margins that have relatively inconspicuous teeth. Leaves occur on long petioles and also have three prominent veins on the upper surface of the leaf that arise from the same point. Stems are erect, branched, stout and covered with a dense cover of short stiff ascending hairs and 'bumps'. Stems are ridged longitudinally and green with maroon to black spots. Stems may reach 6 1/2 feet in height. Flowers are inconspicuous, greenish in color, arising from the area between the leaf petioles and the stems (axillary flowers) and at the ends of the erect stems (terminal flowers). The fruits are elliptic to egg-shaped two-chambered burs, 1/2 to 1 1/2 inches long and covered with hooked prickles. Each bur contains two seeds, one that grows during the first year and one that grows a year later. Two prickles that are longer and wider than the remaining prickles project from the tip of the bur. Cocklebur has a taproot.

Habitats

Cocklebur grows in waste places, cornfields, pastures, and along roadsides, fencerows, stream banks, the beds of dry ponds, and previously flooded land along streams and rivers. Pastures and meadows may be heavily infested, especially with the seedling stage as the result of the burs having been washed in from adjoining fields.

Impacts

Cockle bur seedlings are poisonous to cattle, sheep, horses, and fowl. The plant is most hazardous at the seedling stage because of its toxicity as well as palatability. Ingestion of young seedlings in the amount of 0.75% of the animal's weight may result in clinical signs of toxicosis in a few hours and death in 24-48 hours. Cocklebur is a close relative of ragweed and both the pollen and contact with the leaves can cause allergic reactions in sensitive individuals. Cocklebur can also reduce yield in some crops. The thick, woody stems slow combine speed and decrease harvesting efficiency.

Biology and Ecology

Cocklebur reproduces only from seed. The plant is self-compatible and wind pollinated. Cocklebur seedlings usually emerge in spring, when average soil temperatures are above 15°C, although emergence can continue throughout the summer with adequate moisture. Plants can tolerate frequent flooding and saline soil conditions. Flowering is triggered by day length, and begins in mid-August. The first burs are often ripe in early September, with new flowers and burs forming until a killing frost occurs. Seeds from immature, green burs will still ripen if plants are cut and left in the field. Seed production is proportional to plant size and ranges from several hundred to several thousand seeds per plant. The spiny burs are dispersed to new locations by clinging to animal fur, human clothing, and other material. They are also readily dispersed by water, because the burs contain air spaces that allow them to remain buoyant and float for up to 30 days. Only 1 of the 2 seeds within each bur normally germinates in the year after production, leaving the second seed to re-infest the field in subsequent years. Cocklebur seeds generally do not survive for more than 5 years.

Biological Control

A combination of the rust fungus Puccinia xanthii and a pathogen Collectotrichum orbiculare can cause severe damage to cocklebur leaves.

Mechanical and Cultural Control

Plants in crop fields and pastures may be removed by hoeing and weeding. Heavily infested places should be mowed before the plants form seeds.

Chemical Control

A variety of chemicals are available for control of cocklebur. Please see labels for information on tank mixes. There have been many reports of Organoarsenical and ALS inhibitor resistance in cocklebur in the United States. For a complete list of reports of resistance and information on each report, please see http://www.weedscience.org/Summary/USpeciesCountry.asp?lstWeedID=174&FmSpecies=Go

For herbicide recommendations for specific grain rotations and weeds in Montana, please see the MSU Herbicide Chooser Tool.

Examples of herbicides that can be used to manage cocklebur

Consult herbicide labels for additional rate, application, and safety information. Additional herbicide information can be found at http://www.greenbook.net.

Herbicide Active Ingredient trade name	Mode of Action	Product per Acre	Application Time or Growth Stage
Alfalfa
Imazethapyr	Inhibition of acetolacetate synthase ALS (acetohydroxyacid synthase AHAS)
*Pursuit		4 - 6 ounces	Apply postemergence to seedling alfalfa when alfalfa is in the second (2nd) trifoliate stage or larger and when the majority of the weeds are 1 to 3 inches. Can be applied to established alfalfa in the fall, in the spring to dormant or semi-dormant alfalfa or between cuttings. Any application should be made before significant alfalfa growth or regrowth (3 inches).
XXXXX	Group X:xxxxxx
*XXXXXX		1/2pt/A	XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Dry Peas
Imazamox	Inhibition of acetolacetate synthase ALS (acetohydroxyacid synthase AHAS)
*Raptor		4 ounces	Apply with nonionic surfactant or crop oil, nitrogen based fertilizer and Basagran herbicide. Apply postemergence prior to bloom stage but after dry peas have at least 3 pairs of leaves.
Grass Grown for Seed
Dicamba	Action like indole acetic acid (synthetic auxins)
*Clarity		8 - 64 ounces	Apply 8 - 16 fluid ounces per acre on seedling grass after the crop reaches the 3 - 5 leaf stage. Apply up to 64 fluid ounces on well-established perennial grass. For best performance, apply when weeds are in the 2 - 4 leaf stage.
Small Grains
Fluroxypyr; 2,4-D	Action like indole acetic acid (synthetic auxins)
*Starane+Salvo		1 - 1.3 pints	Apply as a broadcast postemergence treatment to actively growing wheat (including durum) or barley, from the 4-leaf crop growth stage up to flag leaf emergence (Zadoks scale 36) for control of broadleaf weeds. Apply when weeds are actively growing, but before weeds are 8 inches tall.
Rangeland and Pasture
2,4-D; clopyralid	Action like indole acetic acid (synthetic auxins)
*Curtail		2 - 4 quarts	Apply when weeds are actively growing.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

References

For more information and images please visit IPM Bugwood. http://www.ipmimages.org/search/action.cfm?q=cocklebur&Start=1&results=36