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Leafy Spurge

Euphorbia Esula

What is it?

Leafy Spurge is native to Eurasia and was likely introduced multiple times from multiple locations, starting in 1827, and arriving in ship ballasts and contaminated spelt. It is a deep-rooted perennial plant that spreads both vegetatively by extensive creeping roots as well as by seeds. 3-sided seed capsules explode when ripe and project seeds up to 15 feet away from the parent plant. It is an erect plant that grows 1 to 3 feet tall with bluish-green leaves. It is one of the first plants to emerge each spring and steals moisture and nutrients from more desirable species. Major areas of infestation are along county and state roads, as well as along riparian corridors and in meadows and rangelands. It is considered “serious,” “very aggressive,” “most troublesome” and “highly invasive” and is designated as a “List B” species in the Colorado Noxious Weed Act. It is required to be eradicated, contained, or suppressed depending on the local infestations.

Why is it a problem?

Leafy Spurge can have severe negative economic and ecological effects. It threatens sensitive species, replaces native species and negatively impacts species richness. Economic impacts include up to 75% reductions in livestock carrying capacity on lands infected by leafy spurge. It invades fertile meadows, compromising their integrity and ability to support viable populations of native species. It easily colonizes disturbed areas, but can also invade well-managed lands that have dense, vigorous native vegetation. The milky sap produced by leafy spurge can cause diarrhea in cattle and horses. Cattle and horse grazing promotes leafy spurge spread and seedling establishment as a consequence of their selection against it. The sap also causes swelling and burning of the mouth and throat and abdominal pains if ingested by humans. Leafy Spurge’s phenology contributes to its invasiveness. It produces large quantities of seeds which are easily dispersed by animals, insects, wind and water. It thrives in a variety of soil and climate conditions. Its deep root system prevents 100% mortality even from severe fires.

 

 

Management techniques:

Various biological, chemical, cultural and mechanical controls are used to reduce numbers of leafy spurge and restrict vegetative spread. None are a panacea and are most effective when combined:

  • Sheep and goats have been used effectively to control the plant. Cattle and horses will not eat it, but over-grazing of grasses by them makes the grasses much less competitive with leafy spurge.

  • Insects established in the United States include the leafy spurge hawk moth (Hyles euphorbiae), the red-headed leafy spurge stem borer (Oberea erythrocephala), the leafy spurge tip gall midge (Spurgia esulae), and 5 flea beetle species: Aphthona cyparissiae, A. czwalinae, A. flava, A. lacertosa, and A. nigriscutis, all used to reduce abundance. They have been shown to be highly effective in controlling leafy spurge. Knowledge of their unique habitat requirements is important to ensure effectiveness.

  • Repeated cutting and mowing can limit seed production, but may not reduce leafy spurge or restrict vegetative spread. The milky sap can build up in equipment, making this kind of treatment more difficult and less effective. Due to its substantial vegetative growth and clonal spread through root sprouting, pulling is ineffective as it will not remove the entire root system.

  • Leafy spurge is extremely difficult to control with herbicide treatments alone, due to its ability to purge chemicals from its root system. Chemical control of large populations is often cost-prohibitive, but has been used effectively in conjunction with mechanical and biological agents.

 

 

What can we do?

The most effective management tool to fight leafy spurge is to control the spread of it. Early detection of new and small leafy spurge populations should be a top control priority.

  • Well-established populations are rarely completely controlled by contemporary methods. Use only certified weed-free hay, straw and mulch.

  • Clean seeds and root pieces from equipment before moving into uninfested areas.

  • If using sheep and goats to graze leafy spurge, keep them away from uninfested areas until they have passed the seeds (5 days for goats, 9 for sheep).

  • Maintain healthy natural plant communities and reduce land disturbances.

  • Proper timing of herbicide application (in spring when the flowers emerge and in fall) can improve control and help minimize seed production.

 

Entities working on this invasive in the Gunnison Basin:

  • Gunnison Conservation District:

    • -Landowners generated maps of treated areas for the Gunnison County Weed Control Program and completed worksheets with information about species, application rates and environmental conditions. Monitoring assessed the success of the treatments. For more information, contact the Gunnison Conservation District 

 

  • Bureau of Land Management, Weed Management Plan for natural gas facilities in the Bull Mountain unit

    • PDF, describing a weed management plan, that includes Leafy Spurge, for natural gas facilities in the Bull Mountain unit. The Unit is near Montrose, CO in the Lower Gunnison River Basin.

 

 

General Information On Leafy Spurge:

 

 

 

 

 

 

 

 

 

-Offering $100 for the detection of new infestations of leafy spurge within the weed management area

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