HPIPM:Leafy spurge

Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Rosanae
Order	Malpighiales
Family	Euphorbiaceae
Genus	Euphorbia

Scientific Name

Euphorbia virgata

Scientific Name Synonyms

Euphorbia esula

Common Name

leafy spurge

Leafy spurge (Euphorbia esula)

Author: George Beck, Colorado State University Cooperative Extension

Adapted from the Colorado State University Extension Natural Resources Fact Sheet " Leafy Spurge"

Identification and Life Cycle

Leafy spurge (Euphorbia esula) is a perennial forb in the spurge family (Euphorbiaceae). Leafy spurge is an erect plant that grows 1 to 3 feet tall. Umbel flowers are surrounded by heart-shaped, showy, yellow-green bracts. Flowers occur in many clusters toward the top of the plant. Seeds are round to oblong, about 1/12 of an inch long, gray or mottled brown with a dark line on one side. Leaves are bluish-green with smooth margins, 1/4 to 1/2 of an inch wide, and 1 to 4 inches long. Leafy spurge has an extensive root system that is abundant in the top foot of soil, and it may grow 15 feet deep or more. Roots contain substantial nutrient reserves that allow the weed to recover from stress, including control efforts. The many vegetative buds along roots grow into new shoots. This contributes to its persistence and spread. Leafy spurge contains a white milky latex in all plant parts. Latex distinguishes leafy spurge from some other weeds (e.g., yellow toadflax), particularly when plants are in a vegetative growth stage.

Habitats

Leafy spurge occurs under moist to dry soil conditions but is most aggressive under dry conditions. It invades disturbed sites, including prairies, pastures, abandoned fields, and roadsides.

Impacts

Leafy spurge can reduce rangeland cattle carrying capacity by 50 to 75%. About half of this loss is from decreased grass production. Cattle will not graze in dense leafy spurge stands, and these areas are a 100% loss to producers. Leafy spurge is very competitive, one of the first plants to emerge each spring, and uses moisture and nutrients that otherwise would be available for more desirable vegetation.

Biology and Ecology

Leafy spurge shoots originate in early spring from crown tissue just below the soil surface and from sporadic buds along the root system. Flowering occurs primarily in April and May but may occur through fall. Bracts emerge about two weeks before flowers, giving leafy spurge the appearance of flowering. For optimum herbicide application timing, it is important to recognize true flower emergence. Each flowering shoot produces an average of 140 seeds. Seeds are expelled up to 15 feet when dry capsules dehisce. Seeds remain viable for up to eight years in soil. Water, birds, animals, and people aid seed dispersal. Seeds readily float and waterways are good sources for new infestations. Peak seed germination generally occurs in May. Seedlings quickly acquire the ability to reproduce vegetatively by developing buds on roots within 10 to 12 days after emergence. Perennial leafy spurge is more difficult to control than seedlings.

Management Approaches

Leafy spurge is difficult to manage and can recover from almost any control effort. Therefore, a management scheme that combines control methods over four to five years is recommended. Even after that time, monitor infestations for recurrence and adopt a maintenance program. Regardless of the management system used, a combination of methods is essential to return leafy spurge-infested ground to a productive state. The key to control leafy spurge or any creeping perennial is to exhaust the root nutrient stores, causing it to collapse. Persistence is imperative to gain control.

Biological Control

The USDA is examining several insects for leafy spurge control including several flea beetles (Apthona spp.) species, leafy spurge stem-boring beetle (Oberea erythrocephala), leafy spurge hawkmoth (Hyles euphorbiae), and leafy spurge tip gall midge (Spurgia esula). Successful control has been reported with the flea beetles. The hawkmoth has not been effective as a biological control agent and the other agents are still being evaluated. For more information on the biological control agents please see the pamphlet "Noxious Weeds of Nebraska: Leafy Spurge".

Mechanical and Cultural Control

Sheep or goats can be used to help control leafy spurge. Introduce sheep to leafy spurge in early spring when the weed is succulent. Goats will consume leafy spurge at almost any time during the growing season. Rotate pastures to prevent seed production and allow desirable forage plants to regain vigor. If livestock graze leafy spurge after seed formation, hold animals in a corral for at least seven days before moving them to an uninfested area. This reduces viable seed passage. Sheep or goats followed by fall herbicide treatment may be an effective, integrated means to use infested ground and control the weed. Vigorous grass growth is an important aspect of leafy spurge control. Over-grazing stresses grasses and makes them much less competitive with weeds, leafy spurge in particular. Irrigation, where applicable, may favor grass growth and make it more competitive with leafy spurge.

Chemical Control

The distinction between bract appearance and true flowering is important for timing of herbicide applications. Spring-applied herbicides are more effective on plants with developed true flower parts than on plants with developed bracts but undeveloped flowers.

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

Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.

References

For more information and images please visit IPM Bugwood. http://www.ipmimages.org/search/action.cfm?q=Leafy%20spurge