Leafy spurge (State designated weed)

Leafy spurge (State designated weed)

  • Euphorbia esula
  • Euphorbiaceae (Spurge Family)

Leafy spurge is native to Eurasia and was brought into the U.S. as a seed impurity about 1827. It seems to be a serious problem only in North America where it infests almost 2.5 million acres, mostly in southern Canada and the northcentral U.S., including Wyoming. Leafy spurge is one of the most costly noxious weeds in Fremont County where it infests about 10,000 acres. The first infestation was detected in the 1940s in the Squaw Creek drainage west of Lander.

Growth Habit: Perennial; upright, up to 3 feet tall; reproduces by vigorous rootstalks and seed. Seedlings resemble miniature spruce trees.

Leaves: Alternate, narrow, 1 to 4 inches long, usually drooping on thickly clustered stems.

Flowers: Yellowish-green, small, arranged in numerous small clusters and subtended by paired, heart-shaped, yellow-green bracts. The round seed capsule that develops explodes and shoots seeds up to 15 feet from the parent plant. Seeds are viable for eight years and have a high germination rate.

Root: Mature taproots are large, deep, and red-brown; the creeping roots have many pink-red buds that surface to produce new plants. Broken roots are able to generate new plants so plowing or roto-tilling will likely increase the number of plants.

Other: All members of the spurge family have a milky white sap that flows out when any part is broken. The sap may cause blistering on skin, or cause blindness if rubbed in the eyes. It causes severe mouth and digestive tract irritation in cattle if ingested and has caused death. Gardeners who include ornamental species of spurge in their flower beds beware as all types have these same negative attributes.

Status: State Designated Noxious Weed, Category 3 Fremont County. Regional, no tolerance of further spread, control and management of current infestations and aggressive control in areas otherwise free of these weeds.

Control: Certain chemical controls have been effective but are labeled as restricted use pesticides because of environmental concerns. Other chemicals are less effective and have produced mixed results, requiring several reapplications. Two biological controls, the leafy spurge flea beetle and leafy spurge gall midge, are used in Fremont County. FCWP offers an 80 percent Cost Share on chemicals and labor, limited to available funding, through a Leafy Spurge Special Management Program. Contact your local weed and pest office for treatment recommendations.

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