Leafy spurge (Euphorbia esula) Family: Euphorbiaceae Description and VariationDescription and Variation: Leafy spurge is a perennial plant with erect stems 1.5 to three feet tall. These stems originate from a crown just below the soil surface. The plants begin growing in early spring, before their competitors, and tend to appear in patches. Alternate leaves, three inches in length and no more than 1/4 inch wide, crowd along the stem; they are yellow-green from mid-summer to fall, when they turn red with the first frost. Leaves, stems, and roots all exude a milky, irritating sap when broken. In late May or early June, showy yellow bracts appear toward the tips of the short terminal branches, followed in a week or two by inconspicuous small green flowers without petals. Seed production takes about a month and continues until cold weather. Seeds, borne three to a capsule, are about 1/10 inch in diameter, gray to brown in color and often flecked with yellow. The seeds can be shot 20 or more feet when the capsule ripens and explodes. Another unique characteristic of leafy spurge, which contributes to the plants ability to persist once it invades an area, are numerous stem buds which cover the thick very invasive roots. These stem buds can initiate growth when broken into small segments by tillage and are transported by birds, grazing animals, or in soil. Economic ImportanceEconomic Importance: Leafy spurge reduces the livestock carrying capacity of pasture and rangeland by 20 to 50 percent, causing an estimated $35-45 million loss per year in United States beef and hay production in addition to the millions of dollars spent for control. In Europe, natural controls keep leafy spurge from becoming a problem. Geographic DistributionGeographic Distribution: Leafy spurge has been reported worldwide with the exception of Australia. On our continent, it is most troublesome in north central United States and south central Canada. HabitatHabitat: Leafy spurge can survive
under a wide range of unfavorable HistoryHistory: It was initially believed that leafy spurge was introduced to this continent in the early nineteenth century and spread westward through the United States and Canada. The first herbarium specimen was collected in Newbury, Massachusetts in 1827. Examination of more recently collected samples from across North America has shown that leafy spurge is not a single species but an aggregate of closely related variants suggesting that multiple strains were imported at different times from Europe and Asia, probably in grass or cereal seed, or in ship ballast. It appears that leafy spurge of European origin is found along the east coast and that areas of the Great Plains are infested with leafy spurge imported from Russia. Studies are in progress to determine if different control measures are required for plants in various areas. Growth and DevelopmentGrowth and Development: The vigorous
and extensive growth of long roots capable of regeneration provides leafy spurge with the
extraordinary capability to invade, colonize, and persist. North America is essentially
free of the pests and diseases that control this plant in its native European habitat.
Furthermore, leafy spurge is toxic to some animals and unpalatable to most, so it thrives
in areas where competitive plants are heavily grazed. ReproductionReproduction: The female flowers of leafy spurge develop prior to the male, minimizing self pollination. The pollen and nectar are important food sources for insects, and their avid feeding results in high rates of pollination. Seed production is high even when leafy spurge is grown in competition with perennial grasses. Seed maturation often coincides with hay harvest, aiding in the widespread dissemination of the noxious weed. Viability of seed varies with depth of burial; in one representative experiment, more than 50 percent of the seeds recovered from a depth of eight feet germinated, but seed closer to the surface did not survive as well. In addition to very efficient reproduction by seed, leafy spurge spread occurs by crown and root buds. Response to Herbicides: Herbicides are commonly used to control or limit the spread of leafy spurge, but this practice is far from a complete answer. Numerous selective and non-selective herbicides in various combinations or sequences applied with specialized equipment have been evaluated over the years. Some formulations do a good job of controlling top growth but do not effectively kill roots; all are expensive. Control of leafy spurge in established forage grasses can usually be accomplished by spraying with maximum labeled doses of selective herbicides such as 2,4-D, dicamba and picloram, followed by fertilizing to encourage the growth of the forage grasses. Spraying should be done when leafy spurge is between the early bud and first bloom stage and again usually in the fall, when the leafy spurge regrowth is four to six inches high. This routine must be repeated each year until the weed is eliminated. On smaller areas, such as homesites, leafy spurge can be managed with the application of 2,4-D and dicamba when flowers and seeds are developing or with glyphosate alone in midsummer or after fall regrowth, taking care to avoid non-target plants. Response to Cultural MethodsResponse to Cultural Methods: Intensive cultivation and the planting of competitive crops are useful methods for the control of leafy spurge in cultivated fields, but with heavy infestations on rangeland, the addition of chemicals and/or grazing sheep or goats is usually necessary to further diminish weed growth. Biocontrol PotentialsBiocontrol Potentials: The high cost, relative inefficiency, and environmental impact of herbicides have all contributed to a strong interest in natural control systems, such as insects, interspecific competition, and grazing animals. Studies nearly 50 years ago reported that three or more years of continuous sheep grazing significantly reduced the density of established leafy spurge growth. More recently, interest has shifted to the Angora goat, which may provide a good level of weed suppression at less cost than sheep. The major drawback to the approach is the difficulty maintaining sufficient number of sheep or goats to consume spurge plants before they seed but not letting the animals overgraze the grass. Low cost electrical fencing, llamas as sheep herders, and new methods of range weed management are among the many innovations currently being evaluated. Numerous insects and specimens of fungi have been collected from leafy spurge growing in Europe, Asia, and North America and are being evaluated as potential biocontrol agents. The studies are promising. The United State Department of Agriculture selected and released in test plots, five species of insects which attack different parts of the leafy spurge plant; some feed on leaves or stems, others on root crown, shoot tip, or deep secondary roots. Among the insects selected for first round of testing is the ferambyciid long horned beetle, imported from Hungary and Italy, Oberea erythrochphala. The adult feeds of the outside of the plant and girdles the stem. The larvae bore into the stem and rootcrown and consume the inside of the plant. Three species of chrysomelid flea beetles, from central Europe, Aphthona flava, Aphthona czwalinea and Aphthona cyparissiae are in the study group. The adult stage of these beetles feed on leaves for about three months and then the females produce about 250 offspring each, which mine the roots and eat the fine roothairs of the succulent spurge plant. The final member of this voracious quintet is the ceridomyiid midge, a species of Bayeria, a tiny fly whose natural home is Italy. The adult flies live only a day or two but during this time, each generation of females lay about six dozen eggs, which yield larvae that feed on new shoots causing the formation of galls where flowers would normally appear. Together this array of ravenous eaters weaken and destroy the undesirable weed. Research scientists are trying to identify the combination of spurge enemies that achieves maximum control in their experimental plots and then test that recipe on a large scale. It is not expected that biocontrol by itself will lead to the elimination of leafy spurge. The plan to make biocontrol part of an integrated weed management effort which will include competitive planting, cultivation, herbicides, and selective grazing. Leafy spurge is not a problem in its native lands. We should be able to create an environment in North America that restores that noxious weed to its proper place in the plant kingdom. ReferencesReferences: *Adams County Weeders Digest, March 1988. *Agrichemical Age., Leafy spurge on the rampage., December 1986., pg. 21E *Agrichemical Age., Scourge of Leafy Spurge. May 1991. pg.24. *Agri-Times Northwest., Jan. 12, 1990., pg. 5. B.C. Ministry of Agriculture and Food, Field and Special Crops Branch, Kamloops, B.C. Publication Agdex 640. 11-84 Biological Control of Leafy Spurge. USDA program aid #1435. Sept. 1989 *Biological Control of Leafy Spurge. USDA-APHIS-PPQ Bozeman Biological Control Facility Update. Spring 1991. Bishop, Ellen Morris, Sheep: hope of weed control., Capitol Press. Bowes, G. G. and A.G. Tomas, Longevity of leafy spurge seeds in the soil following various control programs. J. Range Manage 31:127-140, 1979. Callihan, Robert H., Joseph P. McCaffrey, Vickie J. Parker-Clark, Leafy Spurge Biology and Management. Univ. of Idaho. Current Information Series #877. *Capitol Press., Idaho uses bioagents, burning chemicals to half leafy spurge., May 31, 1985. Derscheid, L. A., L. J. Wrage and W. E. Arnold, Cultural control of leafy spurge, p. 58. IN Leafy Spurge, Alan K. Watson (Ed). Weed Science Society of America, 1985, Champaign, IL. 104 pp. *Ferrell, Mark A. Thomas D. Whitson, & Harold P. Alley, Control of Leafy Spurge with growth regulator-herbicide combinations. Weed Technology. 1989 Vol. 3:479-484. pg. 479-484. *Fritz, Marlene., Aggressive Weed/Spurge Control, The Growers' Guide, March 1986, pg. 15-16. Lacey, Celestine A. et al. Leafy Spurge, Distribution, Biology and Control Cooperative Extension Service Montana State Univ. Circ. 309. Feb. 1985. *Leafy Spurge Distribution, Biology and Control, Montana State University. Circular 309. February 1985. *Leafy Spurge News., Agricultural experiment station, North Dakota State Univ. March 1989. Vol. 11. *Leafy Spurge News., Agricultural experiment station, North Dakota State Univ., April 1990., Volume 12. *Leafy Spurge News., North Dakota Dept. of Ag., Vol. 13., February 1991. Letourneau, D. & Heggeness, H.G., Germination and growth inhibitors inleafy spurge foliage and quackgrass rhizomes, Weeds 4:12, 1957. *Lym, Rodney G. & Calvin G. Messersmith, Leafy spurge control and herbicide residue from annual picloram and 2,4-D application., Journal of Range Management, May 1987., pg. 194-198. *Lym, Rodney G. & Kevin D. Moxness. Absorption, Translocation, and Metabolism of Picloram and 2,4-D in Leafy Spurge. Weed Science, 1989, Vol. 37:498-502. pg.498-502 *Lym, Rodney G. & Thomas D. Whitson, Noxious Range Weeds. Chapter 19, Chemical Control of Leafy Spurge. pg. 200-209. Westview Press, Boulder, San Francisco, & Oxford. c. 1991. *Moomaw, Russell S. & Alex R. Martin, Ropewick Application of Picloram for leafy spurge control. Weed Technology. 1990 vol 4:235-238. *Moxness, Kevin D., & Rodney G. Lym., Environment and spray additive effects on picloram absorption and translocation in leafy spurge., Weed Science 1989. Vol 37:181-186 *National Gardening Association. The Gardening Journal with Ruth Page. National Gardening Association. c. 1988. *Nielsen, Scott R. Leafy Spurge and its spread in Washington State. pg. 169-175. *One Hundred Years Fact Sheet, Biological control. USDA. March 1989. *Selected Weeds of the United States., USDA Agricultural Handbook No. 366., Reprinted Sept. 1976., pg. 248-249. Steenhagen, D.A. & Zimdahl, R.L., Allelopathy of leafy spurge (Euphorbia esula), Weed Science, 27:1, 1971. *Thompson, Flint, Larry F. Leistritz, Jay A. Leitch., Economic impact of leafy spurge infestations North Dakota. North Dakota State Univ. Agricultural Economics Report #257-S *University of Idaho, Current Information Series No. 323., Leafy Spurge., March 1977. *University of Idaho, Current Information Series No. 877., Leafy Spurge Biology and management., Reprinted 9-91. USDA., Biological control of leafy spurge., Program Aid #1435. Watson, Alan K., Leafy Spurge Monograph Series of the Weed Science Assoc. of America. No. 3. WSS 309 West Clark St., Champagne, IL 61820. Western Society of Weed Science Proceedings., Vol. 45, 1992.
This page last updated 03/31/07 |
conditions. However it spreads most rapidly in areas where cattle or other
grass-preferring animals remove competing plants, permitting leafy spurge to take over by
utilizing the advantages of shooting seeds and invading roots.
