Spotted Spurge and Other Spurges

Integrated Pest Management for Home Gardeners and Landscape Professionals

Spotted spurge ( maculata) is species of spurges appear regularly an annual native to the eastern as weeds in the state—ground spurge United States. In California, it is the (E. prostrata), creeping spurge, petty most common species of the spurge spurge, garden spurge (E. hirta), nod- family, which also includes creeping ding spurge (E. nutans), and thyme- spurge (E. serpens) and petty spurge (E. leafed spurge (E. serpyllifolia). Ground peplus). These weeds invade many of and creeping spurges are troublesome the state’s crops, affecting vegetables, weeds throughout California, while trees, citrus, turf, ornamental beds, and petty spurge is a problem only in container ornamentals. Management of Southern and coastal California land- all the spurges is similar. scapes. Figure 1. Mature spotted spurge is a low-growing plant. IDENTIFICATION All spurges have milky sap, which can be toxic to some animals. Ground Spotted spurge grows close to the spurge (Fig. 4) and creeping spurge ground, often forming a dense mat (Fig. (Fig. 5) grow prostrate like spotted 1). Its dark green , which grow spurge but have no markings on their in pairs called “opposites,” are 1/8 to 1 1 leaves. All spurges reproduce by seed, /2 inch long and about /8 inch wide. and creeping spurge also can produce Frequently a red spot will mark the roots along the stem, creating new halfway down its center vein (Fig. 2). vegetatively. Petty spurge (Fig. 6) is a cool season annual found in shady, Flowers, fruit, stems, and leaves are moist areas, particularly in flower beds. Figure 2. Spotted spurge with red leaf hairy. The short stems have a separate Native to , it grows upright and stipule—or little, scalelike appendage— spots and a broken stem exuding milky is much less invasive than spotted and sap. at their base, although you may need creeping spurge species. Garden, nod- a 10X hand lens to see them. Broken ding, and thyme-leafed spurges cause stems and branches secrete a milky, fewer problems. poisonous sap. Although spotted spurge sap is being studied as a cure There are 18 native species of spurge for various skin cancers, in general, the occurring in various parts of Califor- sap of all members of this genus is an nia. Some of these native species can eye and skin irritant. appear at the edges of cultivated areas adjacent to wildlands, but they are Spotted spurge produces tiny, pink- poorly adapted to cultivated conditions ish flowers (Fig. 3) that consist only of and rarely occur as weeds. and pistils grouped in small, Figure 3. Spotted spurge flowers and flowerlike cups, called cyathia, in the The plant key in Table 1 provides infor- leaf spots. leaf axils, the area where the leaf joins mation to help with identifying spurg- the stem. The fruit is a three-celled es commonly encountered as weeds in seed capsule that is 1/16 inch or less. California. Any weedy spurge collected Each cell contains one seed that is in California that doesn’t appear to about 1/25 inch long. The plant’s central fit these characteristics can be keyed taproot system is capable of extending using The Jepson Manual listed in Refer- more than 24 inches into the soil. ences, or you can take the weed to your local cooperative extension office. The Although spotted spurge is the major Weed Identification Tool available on- spurge weed in California, six other line through UC Davis’ Weed Research Figure 4. Ground spurge plant. EST OTES Publication 7445 PUniversity of California N Statewide Integrated Pest Management Program Agriculture and Natural Resources September 2009 September 2009 Spotted Spurge and Other Spurges

and Information Center (http://weedid. desirable for growth. Once the seed wisc.edu/ca/weedid.php) is an easy-to- germinates, a small rosette of leaves use program useful for homeowners develops. As growth continues, the and professionals. leaves form a dense mat that can grow up to 3 feet in diameter. Reproduc- BIOLOGY tive growth is rapid, and the plant can Most weedy spurges are summer an- produce seeds as soon as 5 weeks after nuals that don’t like competition and germination. depend on their prolific seed produc- tion for survival. A single plant can IMPACT produce several thousand seeds, which Figure 5. Creeping spurge infesting a Spotted spurge can establish itself in field-grown, container plant. are small and can remain dormant in horticultural, agricultural, and non- the soil until conditions are suitable crop sites. It overgrows sparse turf for germination (sprouting). Seeds areas and low-growing ground covers, produced in summer germinate im- invades open areas in gardens and mediately while those produced in late landscapes, and can grow in sidewalk fall mostly will lie dormant and won’t cracks. In addition to reducing the germinate until spring. growth of desirable plants, spotted Spotted spurge germinates best when spurge reduces uniformity and quality temperatures are 75° to 85°F, but ger- of turf, provides a habitat for undesir- mination can occur at temperatures able insects in citrus groves, serves as as low as 60°F and as high as 100°F. an intermediate host for fungal dis- Figure 6. Mature petty spurge. When moisture is available, germina- eases of cultivated crops, and attracts tion can occur from February through ants with its seed. September in most areas of California. MANAGEMENT Light also is a requirement for maxi- Spotted spurge is poisonous and can The primary method of managing mum germination; seeds buried deeper kill sheep grazing in pastures where it spurges is prevention, since control- than 1/2 inch won’t germinate well. is the predominant weed. Sheep that ling these weeds is very difficult once Plants that germinate early in spring consumed as little as 0.62% of their plants have established themselves. in cool conditions can remain as small body weight of this plant have died Avoid bringing seeds into uninfested seedlings until temperatures are more within a few hours. areas by using weed-free planting seed

Table 1. A Key to the Weedy Spurges of California. Flowers (cyathia) Stems erect, to 3 feet tall, sparsely hairy in dense axillary or Nodding Spurge (Euphorbia nutans Lagasca) terminal clusters (generally greater than Stems prostrate with numerous, spreading hairs 10 cyathia per cluster) Garden Spurge (E. hirta L.) Flowers (cyathia) Cyathia, Fruit very sparsely hairy, 1.5–2 mm long; seeds 1–1.25 mm long and wrinkled with low rounded solitary or paired in fruit, ridges; leaves lacking reddish central spot (rare form) leaf axils (Note: Since stem, Thyme-leafed Spurge (E. serpyllifolia Persoon) leaves are opposite, 2 and Fruit distinctly hairy; less than Seeds cross-wrinkled; fruit with appressed hairs to 4 cyathia will be in leaves 1.5 mm long; seed generally over entire surface; leaves generally (greater than 95% close proximity.) hairy less than 1 mm, cross-ridge of plants) with a reddish central spot with narrow sharp ridges, or Spotted Spurge (E. maculata L.) wrinkled; if wrinkled, leaves Seeds cross-ridged; fruit spreading hairy, mostly on usually with reddish central edges only; leaves never with reddish central spot spot (very common species) Ground Spurge (E. prostrata Aiton) Cyathia, Stipules (appendages at leaf base) united into a whitish scale between the leaves; stems almost fruit, always rooting at the nodes; leaf margins smooth-edged or faintly toothed stem and Creeping Spurge (E. serpens Kunth) leaves Stipules separate and hairlike; stems rarely or never rooting at the nodes; leaf margins distinctly hairless toothed, at least near the tip Thyme-leafed Spurge (E. serpyllifolia P.)

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and uncontaminated planting stock. many spurge species. A large, coarse pendimethalin (Pendulum), isoxaben Clean work clothing and machinery bark will require a 3- to 4-inch layer to (Gallery), oryzalin (Surflan), trifluralin such as lawn mowers to remove any be effective; however, larger, coarser (Treflan, Preen), and dithiopyr (Dimen- seeds that might be present, and re- mulches last longer than finely shred- sion). Of these, only pendimethalin, move spurge plants as soon as you ded ones. Thick mulch eventually can trifluralin, dithiopyr, and oryzalin are discover them. accumulate soil, decaying organic available for use by home gardeners. matter, and weed seeds that can germi- Combination products such as oryzalin Cultural Control nate. All organic mulch needs periodic plus benefin are available to both home gardeners and landscape professionals. Weeding or cultivating. Constantly replacement. monitor infested areas, so you can me- Preemergent chemicals are almost chanically till or hand pull new plants Black, synthetic polypropylene weed never used in home vegetable gardens, before they produce seed. Take care as barriers (fabrics or geotextiles), which because chemical residues last for you weed, since plants that you hand are available at nurseries, also block months after application, and product pull often break at the stem, leaving sunlight and starve weed seedlings. labels routinely regulate against such the root and several buds or a single The fabrics are porous to allow water to use. Herbicide recommendations for stem from which regrowth is possible. drain through them. Often a synthetic commercial orchard and vegetable Wear gloves when you hand pull, since barrier with bark or rock on top makes crops are available online; see the UC the sap can be a skin irritant. Mow- the area more aesthetically pleasing. IPM Pest Management Guidelines at ing is an ineffective method of control, Organic mulches such as bark and http://www.ipm.ucdavis.edu/PMG/. since most species grow closely to the straw don’t need to be as thick if you ground. also are using the fabric. Since mulches and weed barriers reduce evaporation Postemergent herbicides available to home gardeners include 2,4-D/MCPP/ When planting new, container-grown from the soil surface, adjust the irriga- dicamba combination products, triclo- ornamentals and ornamental beds, be tion cycle to prevent overwatering. pyr (Turflon), and glyphosate (avail- sure to use sterilized or weed-free able for both commercial and home planting mix. When purchasing plants Turf managment. One of the best con- landscape use). In general, 2,4-D and its for ornamental beds, avoid those with trol measures for spotted spurge in turf combinations don’t control the larger, spotted spurge infestations. Mulches is to maintain a competitive stand of more mature spotted spurge plants. can effectively limit spotted spurge if grass. When open areas develop in turf they prevent light from reaching the due to stress, disease, lack of fertility, seed. insects, or abuse, light penetrates to the soil surface, allowing spotted spurge to Solarization. Before planting an area germinate. Once spotted spurge estab- with turf or ornamentals, you might lishes itself, altering cultural practices want to follow the management meth- such as fertilization or irrigation won’t od known as soil solarization. Covering control it. However, raising the mow- the soil with sheets of clear plastic for 4 ing height to 2 inches or more in tall to 6 weeks during the summer can ef- fescue or perennial ryegrass can reduce fectively reduce the number of seeds in initial invasions. Check turf for exces- areas where summer daytime tempera- sive thatch, which should be less than 1 tures are very hot. In areas where sum- /2 inch high. mer temperatures are lower than 90°F, soil solarization can partially control Food Crops. In home vegetable gar- this weed. For more information, see dens, you can control spurge seedlings References, Soil Solarization for Gardens by using soil solarization, mulches, and & Landscapes. early cultivation.

Mulch. Probably the most common Chemical Control strategy for controlling weeds in or- Preemergent herbicides can help pre- namental plantings is to use organic vent spotted spurge outbreaks if you or synthetic mulches, which prevent apply them in late winter before weed light from reaching weed seeds and seeds germinate. Time the application, seedlings, starving them before they so it occurs before the soil temperature can start making food through photo- exceeds 55° to 60°F at a depth of 1 inch. synthesis. Bark, compost, or straw laid at least 2 inches thick can effectively Preemergent herbicides for turf and control many weed seeds including ornamentals include benefin (Balan),

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SUGGESTED READING Armstrong, W. P. The Euphorbia Fam- ily (): A Large & Diverse Family of Flowering Plants. Palomar Community College District. Available online, http://waynesword.palomar.edu/ trmar98b.htm. Accessed September 2009.

Derr, J. F. 1994. Weed control in con- tainer grown herbaceous perennials. Hort. Sci. 29(2):95–97.

DiTomaso, J. M., and E. A. Healy. 2007. Weeds of California and Other Western States. Oakland: Univ. Calif. Agric Nat. University of California scientists and other Res. Publ. 3488. AUTHORS: R. H. Molinar, UC Cooperative Extension, Fresno Co.; D. W. Cudney, Bot- qualified professionals have anonymously peer reviewed this publication for technical accuracy. The any and Plant Sciences emeritus, UC River- Elmore, C. L., and J. A. Roncorni. 1986. ANR Associate Editor for Urban Pest Management side; C. L. Elmore, Plant Science emeritus, managed this review process. Postemergent control of Euphorbia mac- UC Davis; and A. Sanders, Herbarium, UC To simplify information, trade names of products ulata (spotted spurge). West. Soc. Weed Riverside. have been used. No endorsement of named products is intended, nor is criticism implied of similar products Sci. Res. Prog. Rep. p. 84. that are not mentioned. TECHNICAL EDITOR: M. L. Flint This material is partially based upon work Elmore, C. L., J. J. Stapleton, C. E. Bell, supported by the Extension Service, U.S. Department EDITOR: M. L. Fayard of Agriculture, under special project Section 3(d), and J. E. DeVay. 1997. Soil Solarization: A Integrated Pest Management. Nonchemical Method for Controlling Dis- ILLUSTRATIONS: Figs. 1-3 and 5-6, J. K. eases, Nematodes, and Weeds. Oakland: Clark; Fig. 4, J. M. DiTomaso, and Table 1, Produced by UC Statewide Univ. Calif. Agric. Nat. Res. Publ. 21377. M. Brush. Integrated Pest Management Program University of California, Davis, CA 95616 Koutnik, D. L. 1993. Chamaesyce. In J. C. Hickman, ed. The Jepson Manual: This and other Pest Notes are available at www.ipm.ucdavis.edu. Higher Plants of California. Berkeley: For more information, contact the University of Univ. Calif. Press. California Cooperative Extension office in your county. See your telephone directory for addresses University of California and phone numbers, or visit http://ucanr.org/ce.cfm. Agriculture and Natural Resources Program Molinar, R. 2002. California Master Gar- dener Handbook. Oakland: Univ. Calif. WARNING ON THE USE OF CHEMICALS Agric. Nat. Res. Publ. 3382. Pesticides are poisonous. Always read and carefully follow all precautions and safety recommendations given on the container label. Store all chemicals in the original, labeled containers in a locked cabinet or shed, away from food or feeds, and out of the reach of children, unauthorized persons, pets, and livestock. Ohio State University. Controlling Pesticides applied in your home and landscape can move and contaminate creeks, rivers, and oceans. Weeds in Nursery and Landscape Confine chemicals to the property being treated. Avoid drift onto neighboring properties, especially gardens Plantings. Bulletin 867. Available online, containing fruits or vegetables ready to be picked. Do not place containers containing pesticide in the trash or pour pesticides down the sink or toilet. Either use http://ohioline.osu.edu/b867/b867_3. the pesticide according to the label, or take unwanted pesticides to a Household Hazardous Waste Collection html. Accessed September 2009. site. Contact your county agricultural commissioner for additional information on safe container disposal and for the location of the Household Hazardous Waste Collection site nearest you. Dispose of empty containers by following label directions. Never reuse or burn the containers or dispose of them in such a manner that Sholedice, F., and M. Renz. 2006. Spot- they may contaminate water supplies or natural waterways. ted Spurge. O&T Guide W-16. New State University. Available on- NONDISCRIMINATION STATEMENT line, http://cahe.nmsu.edu/ces/plant- The University of California prohibits discrimination or harassment of any person on the basis of race, color, national origin, religion, sex, gender identity, pregnancy (including childbirth and medical conditions clinic/documents/spotted-spurge-w-16. related to pregnancy or childbirth), physical or mental disability, medical condition (cancer-related or pdf. Accessed September 2009. genetic characteristics), ancestry, marital status, age, sexual orientation, citizenship, or service in the uniformed services (as defined by the Uniformed Services Employment and Reemployment Rights Act of 1994: service in the uniformed services includes membership, application for membership, performance of Stapleton, J. J., C. A. Wilen, and R. H. service, application for service, or obligation for service in the uniformed services) in any of its programs Molinar. Oct. 2008. Pest Notes: Soil So- or activities. University policy also prohibits reprisal or retaliation against any person in any of its programs or activities larization for Gardens & Landscapes. Oak- for making a complaint of discrimination or sexual harassment or for using or participating in the investigation land: Univ. Calif. Div. Agric. Nat. Res. or resolution process of any such complaint. Publ. 74145. Also available online, www. University policy is intended to be consistent with the provisions of applicable State and Federal laws. Inquiries regarding the University’s nondiscrimination policies may be directed to the Affirmative Action/ ipm.ucdavis.edu/PMG/PESTNOTES/ Equal Opportunity Director, University of California, Agriculture and Natural Resources, 1111 Franklin Street, pn74145.html. Accessed July 2009. v 6th Floor, Oakland, CA 94607, (510) 987-0096.

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