Southern sandbur [Cenchrus echinatus L.][CCHEC][CDFA list: C] Photographs

Field sandbur or Coast sandbur [Cenchrus incertus M. Curtis][CCHIN][CDFA list: C]

Longspine sandbur or Mat sandbur [Cenchrus longispinus (Hackel) Fern.][CCHPA][CDFA list: C] Photographs

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GENERAL DESCRIPTION:Introduced summer annuals, to 0.6 m tall, with loose spikes (racemes) of spiny burs at maturity. Field sandbur is annual in CA, but can be biennial or perennial elsewhere. Plants provide good forage for livestock before burs develop. However, bur spines are stiff and can injure the mouths of animals and the hands and feet of people working in infested crops, orchards, or vineyards. Field and longspine sandburs are similar and difficult to distinguish.

SEEDLINGS:Leaves folded in bud. Sheaths, ligules, and blades resemble those of mature plants.

MATURE PLANT:Loosely tufted. Culms branched and often abruptly bent near the base (geniculate). Ligules consist of a fringe of hairs, 0.5-1.5 mm long. Often there is a tuft of hairs ~ 2-3 mm long at the position of the auricles. Sheaths open, flattened, +/- glabrous, margins narrowly membranous, sometimes lined with a few long hairs. Collar narrow, lighter in color. Blades flat, sometimes folded, appear +/- glabrous, but are rough with very short hairs (visible with magnification).

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ROOTS and UNDERGROUND STRUCTURES:Roots fibrous, shallow. Sometimes roots at the nodes.

SPIKELETS/FLORETS:Spikelets (1-8) enclosed by fused, spiny bracts that form a bur. Racemes of burs loosely spike-like, terminal. Main flowering axis (rachis) wavy. Burs disperse as units. Upper leaves sometimes partially enclose the lower burs. Spikelets consist of 2 florets. Only the upper floret is fertile.

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POSTSENESCENCE CHARACTERISTICS:southern sandbur: Late in the season, lower foliage becomes straw-colored and stems turn reddish or maroon. After a frost, entire plants become straw-colored. Stems with burs can persist through winter. Dispersed burs can remain on or near the soil surface through the following summer.

HABITAT:Aggressively colonizes open, disturbed sites in fields, orchards, vineyards, alfalfa, cultivated crops, ditch banks. Often infests sandy, well-drained soils.


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PROPAGATION/PHENOLOGY:Reproduces by seed. Burs disperse by clinging to skin and fur of animals, shoes and clothing of humans, tires, farm machinery, and by floating on water. Seedlings emerge in spring or early summer, and growth is rapid under moist conditions.


MANAGEMENT FAVORING/DISCOURAGING SURVIVAL:Sandburs compete poorly with dense vegetation and rarely become established in well-managed pastures. Disturbances that bury burs and remove existing vegetation stimulate germination and enhance seedling establishment. However, repeated cultivation before burs develop reduces the seed bank and can eventually eliminate an infestation. Under mowing regimes, plants grow low to the ground and can still produce burs.

SIMILAR SPECIES:Unlike the sandburs, bufflegrass [Cenchrus ciliaris L.][PESCI] has stiff-bristly bracts separate to near the base and straight main flowering axes. Bufflegrass is a perennial with rhizomes and sometimes stolons. It infests disturbed sites and fields in the South Coast region (Los Angeles Co.) to 100 m (330 ft) and is increasing in distribution in many areas in the Southwestern U.S. Bufflegrass is especially troublesome in southwestern deserts that receive summer rain. Introduced from Africa and India.


Biology and prevention: Three weedy Cenchrus species occur in California. They are found in irrigated crops and along roadsides and disturbed areas. The spiny burs are a nuisance to farm workers and may cause injury and seriously interfere with crop harvests, resulting in increased costs and decreased productivity. Burs are troublesome to animals; they are easily caught in hair, fur, and wool, and reduce wool quality and cause injury to livestock, wildlife and pets.
Seed dispersal occurs by animals, farm equipment, tires, and in contaminated hay and other forage crops. Water is also important for dispersal, as burs float and may be carried for miles in irrigation ditches and other waterways.
All three species are normally annuals with the exception of C. incertus, which may overwinter as a short-lived perennial. Nevertheless, all are subsequently dependent upon seed production for survival. Individual plants can produce more than 5,000 burs, with 1-3 seeds per bur. Plants produce (primary) seed with low dormancy and (secondary) seed with higher levels of dormancy. Light may inhibit germination and cause induced dormancy in secondary seed. Seed viability is believed to be short, but may be up to three years. Seedlings generally emerge in the spring, but additional seedling flushes can occur with irrigation or late season rainfall.

Mechanical: Tillage is effective when plants are small. However, large plants of all three species may root at the nodes, resulting in large tussocks that are difficult to sever. Tillage may also increase seed germination by burying seed on the soil surface where light inhibits germination. Intensive cultivation throughout the season following each flush of seedlings has been used for eradication, but may take up to three years. Deep plowing is effective; however, seed may germinate from depths of 11 cm.
Repeated mowing or heavy grazing prior to flowering will reduce, but not eliminate seed production. Animals will avoid grazing mature plants, which can result in serious mechanical injury if no other forage is available. Mowing is most effective when plants are at the boot stage of development.

Biological: There are no biological control agents for sandbur. Sandbur does not compete well in shaded conditions and maintaining a dense cover in pastures can prevent invasion. Most competitive forage crops may reduce but not eliminate seed production by established plants.

Fire: There is little information on utilizing controlled burns for sandbur management. However, flaming is an effective control technique when conducted prior to seed set.

: There are several herbicides registered for sandbur control in California. However, their utilization is dependent upon the cropping situation. Nonselective treatments include glyphosate (0.75-1.5 lb ae/A) and diuron (2.7-7.5 lbs ai/A); bromacil (5-6.2 lb ai/A) in citrus; benefin (3.3-4.1 lb ai/A) in lettuce and alfalfa; fluazifop (0.25-0.375 lb ai/A) in several fruit, nut, and vegetable crops; trifluralin (0.36-1.0 lb ai/A) in certain crops; and MSMA (1.8 lb ai/ 40 gallons water, spray to runoff) in non-crop areas. There are currently no known cases of herbicide resistance in any species of Cenchrus. However, repeated applications of the same herbicide or same mode of action may select for resistant plants.

Anderson, R. L. 1997. Longspine sandbur (Cenchrus longispinus) ecology and interference in irrigated corn (Zea mays). Weed Technology 11:667-671.
Boydston, R. A. 1989. Germination and emergence of longspine sandbur (Cenchrus longispinus). Weed Science 37:63-67.
Boydston, R. A. 1990. Time of emergence and seed production of longspine sandbur (Cenchrus longispinus) and puncturevine (Tribulus terrestris). Weed Science 38:16-21.
Hickman, J. C. 1993. The Jepson Manual. Higher Plants of California. Berkeley, CA: University of California Press.
Martins, C. C., Velini, E. D., and Martins, D. 1997. Dormancy breaking in southern sandbur seeds. Planta Daninha 15:61-71.
McKinney, K. K. and Fowler, N. L. 1991. Genetic adaptations to grazing and mowing in the unpalatable grass Cenchrus incertus. Oecologia 88:238-242.
Parsons, W. T. and Cuthbertson, E. G. 1992. Noxious Weeds of Australia. Melbourne: Inkata Press.
Twentyman, J. D. 1972. Notes on two species of Cenchrus (Gramineae) in Australia. Muelleria 2:164-168.
Twentyman, J. D. 1974. Environmental control of dormancy and germination in the seeds of Cenchrus longispinus (Hack.) Fern. Weed Research 14:1-11.
Twentyman, J. D. 1974. Control of vegetative and reproductive growth in sandbur (Cenchrus longispinus). Australian Journal of Experimental Agriculture and Animal Husbandry 14:764-770.

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