Leafy Spurge (Euphorbia esula)

County Management Strategy: Eradication throughout the County.

Identification: A perennial with extensive, deep, creeping rootstocks. Roots are dark brown with pink shoot buds. Leaves are linear and about 1-1½ inches long. Flowers are inconspicuous and green. At the base of the true flowers, and emerging before them, are bright yellowish-green bracts that are often mistaken for the flowers. It is very important to distinguish these two stages for timing control work. Seeds are in a pod, which when dry expels the enclosed seeds up to 15 feet. The plants have a milky latex sap which is very toxic.

Other names: Spurge

Similar Species: Leaves are similar to yellow toadflax. Other spurges in our area are either low growing (prostrate spurge) or have broad, toothed leaves (toothed spurge). Many plants have milky sap so this is not a good diagnostic tool.

Control Timing: When bracts are present but before true flowers emerge (late spring) and in the fall.

Control target: Prevent seed production and stress root system.

Control Methods: Herbicides and competitive plantings are the most effective methods of control for leafy spurge. Small infestations should be sprayed immediately and repeatedly after allowing regrowth to occur. CSU Extension Fact Sheet No. 3.107 details control methods. Grazing by goats has worked well in some situations. Several species of Apthona flea beetles have proved to be very effective in some parts of the country. However, biological control is not recommended in Mesa County because eradication is the management goal for this species. Large infestations are the best candidates for release of biocontrol agents. Application of herbicide to the perimeter of a infestation may be necessary to keep the weed from spreading while the beetles establish and build their numbers.

Status in Mesa County: Current infestation is in the Plateau Valley area near mile marker 3 on Highway 330. A small infestation was found in 2001 west of the town of Mesa. A ¼ acre patch was found in 2007 south of Mesa. A small, dwindling population also occurs in Unaweep Canyon, west of the Divide Road turnoff.

Toxicity: The milky sap of leafy spurge can cause skin and eye irritation in humans and other animals. It can cause death of livestock. The toxicity remains even after the plants are dried. Caution must be taken when handling this weed. REPORT INFESTATIONS TO THE DIVISION OF PEST MANAGEMENT!

Photos:
http://extension.usu.edu/weedweb/ident/Lspurg_id.htm

Fact sheets and control:
http://www.nps.gov/plants/alien/fact/eues1.htm
http://www.ext.nodak.edu/extpubs/plantsci/weeds/w866w.htm
http://www.ext.colostate.edu/pubs/natres/03107.html

Additional Links:
http://www.ceris.purdue.edu/napis/pests/ls/