- Sally Asked
- The Gardener’s Answer
- Removing Cockleburs
- The Remarkable Cocklebur
- Cocklebur (Xanthium strumarium)
- Identification and Life Cycle
- Biology and Ecology
- Management Approaches
- Mechanical and Cultural Control
- Chemical Control
- Examples of herbicides that can be used to manage cocklebur
What is the best way to get rid of cockleburs from the garden?
The Gardener’s Answer
Hi, Sally: Cocklebur (Xanthium) belong to the Asteraceae family. These annual weeds are commonly found in pastures and ditches. They can be a real nuisance and pose a threat to any livestock. Cockleburs flower during the late summer into the fall and eventually the hard spiny burrs develop, usually containing two seeds each. One of these seeds will germinate this spring and the second will not germinate until the following spring. Not allowing them to flower is key to eliminating seed dispersal, which is its only means of reproduction. Unfortunately these burrs will attach themselves to anything they touch so distribution is not limited. Effective control methods will depend on individual situations but spot spraying with a pre-emergent as well as a post-emergent herbicide such as Round-up containing 2,4-D and or glyphosate, specifically made for broadleaf weeds, is an option. Corn gluten is an organic option as a pre-emergent. As with all pre-emergents they do not allow seeds to germinate so it should not be used where you have intentionally planted seeds. These plants have taproots so hand digging is not the best option. Mowing the area, if possible, will prevent the weeds from flowering, which will prevent future plants but not for immediate control. It will take a few years to eliminate these weeds but keep in mind that weeds are easier to control as they first emerge.
Have a question for the Gardener?
Here on the BackyardRanch, cockleburs have been a problem. Our weed control program is working but very slow. We are on constant cocklebur removal from our little remuda, and will be until we get rid of all the cocklebur plants. Cockleburs are a broadleaf weed that produces a small egg shaped spiny bur. These burs get tangled in horse hair worse than anything I have seen. They make a huge spiny mat as several of them get tangled up. After the hair is so tangled, they are nasty to remove. Making scissors and sacrifice of mane and tail a viable option.
We have found a way to remove the cockleburs from horse manes and tails. You will need some inexpensive tools: cooking oil/corn oil, a squeeze bottle and a horse hair comb or horse hair rake. Pour the cooking oil in the squeeze bottle.
Start combing at the bottom of the mane or tail and comb up to the bottom of the burr or mat. This way the bur will slide free of the rest of the hair. Pour the cooking oil from your squeeze bottle just above and onto the mat and burs, doesn’t take much. Use the comb or rake to comb out the burs from the mat. It takes some coaxing.
Make sure that when the burs are removed that you get rid of them or where they land, another plant will grow with dozens more cockleburs. They can go in the fireplace, branding fire or woodstove.
After Cocklebur Removal
Rinse the excess cooking oil out of the mane and tail with a good quality horse shampoo and conditioner. It is important to keep the mane and tail groomed at this point forward to keep cockleburs from creating such a mat. They should slide out easier from groomed horse hair.
The backyard ranch horses like this way to remove the cockleburs from their
manes and tails much better than us spending all day sorting and pulling hair with sore fingers pulling out the burs. Dry combing the burs out yanks the mane and tail hair out. Cutting the mane and tail prevents the horse from chasing off biting insects.
You see, cocklebur is an annual. It only has one season to germinate, grow, flower, and produce the next generation. We often think of annual plants as being hardy but in reality, they are often a bit picky about when and where they will grow. For that reason, seed banking is super important. Not every year will produce favorable growing conditions so dormant seeds lying in the soil act as an insurance policy.
Whereas the bottom seed germinates within a year and maintains the plants presence when times are good, the top seed appears to have a much longer dormancy period. These long-lived seeds can sit in the soil for decades before they decide to germinate. Before humans, when disturbance regimes were a lot less hectic, this strategy likely assured that cocklebur would manage to stick around in any given area for the long term. Whereas fast germinating seeds might have been killed off, the seeds within the seed bank could pop up whenever favorable conditions finally presented themselves.
Today cocklebur seems to be over-insured. It is a common weed anywhere soil disturbance produces bare soils with poor drainage. The plant seems equally at home growing along scoured stream banks as it does roadsides and farm fields. It is an incredibly plastic species, tuning its growth habit to best fit whatever conditions come its way. As a result, numerous subspecies, varieties, and types have been described over the years but most are not recognized in any serious fashion.
Sadly, cocklebur can become the villain as its burs get hopelessly tangled in hair and fur. Also, every part of the plant is extremely toxic to mammals. This plant has caused many a death in both livestock and humans. It is an ironic situation to consider that we are so good at creating the exact kind of conditions needed for this species to thrive. Love it or hate it, it is a plant worth some respect.
The Remarkable Cocklebur
Probably everyone has gotten cockleburs in their socks or clothing, especially if you enjoy walking in riverbed areas or along cultivated fields and moist pastures. Cocklebur plants (Xanthium strumarium) produce hundreds of little football-shaped burs, about one inch (2.5 cm) long and covered with stiff, hooked spines. Each cocklebur fruit contains two seeds that may remain viable for many years. The prickly burs hook into your clothing and become tightly attached, like the Velcro® fasteners on shoes and day packs. Often the vicious burs form tangled clots in the fur of animals, and must be cut out of the hair. In fact, these remarkable burs have enabled the cocklebur plant to hitchhike all over the world.
A cocklebur plant (Xanthium strumarium) bearing prickly, hitchhiker burs.
There is some disagreement among botanists as to exactly how many varieties of common cocklebur (Xanthium strumarium) exist, and precisely where is their native (indigenous) habitat. There are several named varieties listed in botanical literature, including var. canadense and var. glabratum; however, some authorities believe Xanthium strumarium is one cosmopolitan species with many highly variable populations around the world. Since cockleburs can colonize new areas quite easily (particularly disturbed areas), they are good examples of the “founder effect.” The founder effect is genetic drift that occurs when a small number of individuals, representing a fraction of the gene pool, establish (found) a new colony and only certain alleles (genes) of the original population are passed on to the next generation. The founding colony does not have the genetic variability of the main population, and the frequency of certain traits may increase greatly by genetic drift compared with the much larger ancestral population. A classic example of the founder effect is the “Dunkers,” a politically incorrect name for a German Baptist religious sect that settled in Franklin County, Pennsylvania between 1719 and 1729. Since the original families (who did not marry outside their religious sect) settled in Pennsylvania, there has been a dramatic change in some of their gene frequencies. For example, the frequency of type A blood in the “Dunkers” is now 60 percent, compared to 42 percent for the United States and 45 percent for West Germany. The founder effect also explains the high frequency of dwarfism and polydactylism (extra fingers) in the Amish of Lancaster Pennsylvania, a colony begun by a few individuals (at least one of whom carried these traits). There is some evidence that the first humans to reach North America (across the Bering Straits land bridge) brought with them gene frequencies not representative of the Asiatic population they left. The unusual variation in bark, foliage and growth characteristics in isolated groves of cypress (Cupressus species) throughout coastal and mountainous regions of California may also be due (in part) to the founder effect; however, some traits, such as glandular (resinous) foliage, are more drought resistant and probably evolved by natural selection in the hot, dry interior regions of the state.
An assortment of prickly cockleburs (Xanthium strumarium).
The cocklebur is a classic example of a short-day plant (i.e. it only flowers when the nights are long). At least one leaf of a cocklebur plant needs 15 hours of darkness to undergo various complex biochemical reactions leading to the release of a hypothetical flower stimulant called “florigen.” A protein leaf pigment called “phytochrome” controls the release of florigen from the leaves. One form of this pigment (P-660) is formed during the hours of darkness and is essential for the release of florigen. The phytochrome P-660 pigment is very sensitive to specific wavelengths of light, and a flash of light during the 15 hours of darkness can instantaneously convert it into another form called P-730 which inhibits the release of florigen, thus blocking the flowering process. Cocklebur plants can bloom in the tropics where the days are short and the nights are long, thus greatly increasing its range and potential for seed production. In North America cockleburs typically bloom during the fall months when the days are shorter and the nights longer. They will not bloom during the long days of summer or near a street light.
Shoes and socks after walking through a field of cockleburs.
Cockleburs belong to the enormous sunflower family (Asteraceae), the largest plant family with approximately 24,000 species. The seeds are typically enclosed in a one-seeded fruit, called an achene, which is often airborne with a plume of silky hairs resembling a miniature parachute. In the cocklebur, the achenes are enclosed in a bur or involucre that is covered with hooked prickles. Another related hitchhiker in the sunflower family, called burdock (Arctium lappa), is equally adapted for clinging to animals and inanimate objects. Like the cocklebur, its hooked prickles are very difficult to remove from a shag carpet or sweater. Other hitchhikers, such as bur clover (Medicago hispida) and teasel (Dipsacus sativa) belong to the legume family (Fabaceae) and teasel family (Dipsacaceae). Teasel bristles are stiff enough to raise and straighten the nap on woolen cloth. The large, spiny heads of teasel were used in carding wool in early days. The heads were split and mounted on belts or rollers that moved over the cloth.
A. Cocklebur (Xanthium strumarium); B. Burdock (Arctium lappa); C. Bur Clover (Medicago hispida). Note the curved prickles that hook into the fiber of clothing like a Velcro® fastener.
The tenacity of common burdock (Arctium minus) was described in an article by J. Raloff in Science News Volume 154, 1998. Burdocks are well-known for their ability to stick to bare fingers, but actually trapping an animal was unheard of. While migrating through Rock Creek Park in Washington, D.C., four ruby-throated hummingbirds became entangled in clusters of burdock fruits near the tops of this prolific weed that can grow to 6 feet (2 m). One of the birds was rescued, but the other three were so securely snared by the hooked prickles that they died right on the plants. The birds were unable to fly away, and their struggling caused them to touch other burs, ensnaring them even more. A thicket of burdock plants poses a potential death trap to small birds that might land on a cluster of the spiny burs.
Burdock (Arctium lappa) in full bloom. Like the cocklebur, the one-seeded achenes of burdock are enclosed in a bur or involucre that is covered with long spines which are hooked at the tip. The dried burs readily cling to the fur of animals or clothing, thus making this plant one of nature’s most successful hitchhikers. The minute hooks at the tips of the spines can even penetrate the dead layer of skin on your fingers. Note the katydid (order Orthoptera) that was feeding on this plant.
Oone of the most amazing stories about hitchhiking plants is the origin of the fastener known as Velcro®. We are not sure whether this remarkable invention came from the cocklebur (Xanthium), burdock (Arctium), bur clover (Medicago hispida), teasel (Dipsacus sativus) or another species of “bur,” but this amazing discovery is certainly pertinent to any discussion about hitchhiking plants.
Teasel burs (Dipsacus sativus). In real life they do not hatch from eggs.
One day in 1948, an amateur Swiss mountaineer and naturalist, George de Mestral, went on a nature walk with his dog through a field of hitchhiking bur plants. He and his dog returned home covered with burs. With an intense curiosity, Mestral went to his microscope and inspected one of the many burs stuck to his pants. He saw numerous small hooks that enabled the seed-bearing bur to cling so tenaciously to the tiny loops in the fabric of his pants. George de Mestral raised his head from the microscope and smiled thinking, “I will design a unique, two-sided fastener, one side with stiff hooks like the burs and the other side with soft loops like the fabric of my pants. I will call my invention Velcro® a combination of the words velour and crochet. It will rival the zipper in it’s ability to fasten.”
Microscopic view of the two sides of a Velcro® fastener. The numerous hooks (left) become embedded in the meshwork of loops (right). This is essentially how many plant hitchhikers (such as cockleburs) adhere to your clothing. The hooks on the cockleburs attach to the meshwork of threads in your socks. In fact, the original inventor of velcro came up with his marvelous invention after an encounter with a plant hitchhiker. Copyright (c) W. P. Armstrong.
Mestral’s idea was met with resistance and even laughter, but the inventor “stuck” by his invention and together with a weaver at a textile plant in France, Mestral perfected his “hook and loop fastener.” By trial and error he realized that nylon when sewn under infrared light, formed tough hooks for the bur side of the fastener. This design was finally patented in 1955. The inventor formed Velcro Industries to manufacture his invention and soon started selling over 60 million yards of the product each year. Today Velcro Industries is a multi-million dollar company.
Athough the word “velcro” was originally use by George de Mestral for his novel invention, it has become a common household word synonymous for “hook and loop” fasteners for clothing, shoes, straps, packs and numerous other products. Today Velcro® is the registered trademark for Velcro Industries’ products, but there are other brands of similar fasteners on the market. Many people in the United States refer to facial tissue as “kleenex” because this was one of the original and popular brand names. But Kleenex® is the registered trademark of one brand of facial tissues, and there are other registered brand names, each manufactured by different companies. This illustrates a problem Velcro Industries and other inventors face when the names of their products become generic terms. Many words used frequently in everyday language were once trademarks, for example “escalator,” “thermos,” “cellophane,” and “nylon.” When names become generic terms, the U.S. Courts can deny exclusive rights to the trademark, so that other companies can produce the same type of product under a different registered brand name.
In order to protect a name it should be officially registered with the U.S. Patent and Trademark Office. When officially registered, the name is followed by ® (an R with a circle around it). Otherwise someone else can use your name for their product. This is precisely why the name Wayne’s Word® is an official registered trademark; however, it is doubtful that it will ever become a household name like cellophane or Velcro®.
Cockleburs have literally hitchhiked across Europe and North America. In some lowland areas it is considered to be a troublesome weed by farmers and ranchers. But there may be at least two interesting uses for cockleburs. Because they readily attach to cloth material, they can be used as “darts” in a cocklebur dart game, and sixteen of the spiny burs can be glued together to form a perfect little poodle dog.
Go To Ultimate And Most Painful Hitchhikers
Xanthium strumarium L. (Aster family, Asteraceae)
Warm-season annual forb 2 to 4 feet tall and little branched, except for short side stems appearing from the leaf axils; stems round or slightly ribbed; often speckled with purple and have short white hairs scattered across the surface; root system consists of a taproot that is stout and rather woody.
Leaves: The alternate leaves are up to 8 inches long and 6 inches across; cordate or ovate-cordate shaped, with bases that are well rounded or indented and tips that are broad and blunt; margins are shallowly lobed or coarsely toothed, while the upper surface has a sandpapery texture; each leaf has a long petiole that is often reddish or reddish green and about as long as the leaf blade; petioles usually have short white hairs.
Flowers: Flowers July to September; flower heads are small; in the axils of the upper leave; flowers are of two types, male and female flower heads separate; male flower heads about 1/4 inch across, female flower heads about 1-1/2 inches long and 1 inch across; flowers are green.
Fruit: Fruits are a 3/8 to 13/16 inch long, woody bur, with hooked prickles and 2 curved spines at the tip; 2-seeded; dark brown seeds are flattened and pointed at the tips.
Cultivated and disturbed or degraded dry sites in meadows, grasslands, woodlands, and chaparral communities, and roadsides within elevations that generally range below 6,300 feet.
Reproduces by seed; cocklebur is one of nature’s original “velcros.”
Native to North America; young seedlings of common cocklebur exude toxic chemicals that can inhibit germination of other species of plants, or kill off their seedlings; individual plants become less toxic as they mature: spiny cocklebur is a closely related and similar species, however, unlike common cocklebur, this weed has the very distinctive 3-parted spines that arise at the base of each leaf. This species generally occurs as a weed in wildland areas of the Southwestern Region rather than as an invasive plant.
Taxonomy Kingdom: Plantae Phylum: Magnoliophyta Class: Magnoliopsida Order: Asterales Family: Asteraceae Genus: Xanthium Species: X. strumarium Subspecies: X. strumarium Scientific Name Xanthium strumarium
L. Scientific Name Synonyms Xanthium strumarium var. strumarium
Common Names common cocklebur, cocklebur, cockleburr, rough cocklebur
Cocklebur (Xanthium strumarium)
Compiled by Steve Lackman, Montana State University, Yellowstone County Extension
and Marjolein Schat, Montana State University from the following sources:
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.
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.
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.
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.
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|
|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).|
|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.
|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.