Idaho Weed Awareness Campaign
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Leafy Spurge

The Enemy - Leafy spurge (Euphorbia esula) is a weed  that most of us will face. It is a very deep, up to 30 feet, perennial plant that spreads by creeping roots and can launch its seeds up to 15 feet. The seeds are mostly spread by small birds. In fact it can send up a runner from the root from as deep as 10 feet. It has a very distinct yellow/green color at the flower head, which can be most noticeable from long distances. The plant produces a milky juice throughout the entire plant. It has dark green narrow simple leaves that originate from the main stem. In the late summer the plant loses its leaves and leaves behind a red to orange stem. It is grows in dry areas and moist areas and non-disturbed areas and disturbed areas and ditch banks and roadsides and riparian areas and gardens and lawns.

The Attack - This plant is toxic to most animals that eat it. The milky juice is known to cause serious eye damage in humans and animals. It also can cause blisters around the lips of animals. The plant rapidly becomes a solid monoculture of which no other plants can invade. It can single handily take out desirable grasses, forbs and shrubs, and trees. Parts of Idaho, Montana, and the Dakotas have lost thousands of acres of land to this nasty invader.

The Defense - This plant is extremely difficult to control due to its very extensive root system. It takes all the tools in our weed tool box to control it. Some have tried goats and sheep, others utilize insects, many utilize herbicides such as Tordon® 22K (RUP), Plateau in the fall, Banvel plus 2,4-D. The fact is, all these combined is best other than keeping it from invading.

ERADICATING LEAFY SPURGE

Herbicide Control - There are several effective herbicides to control leafy spurge.

DOW LogoTordon® 22K at 2-4 pt/A Apply at true flower stage of growth or apply to fall regrowth. Re-apply when level of control falls below 80 percent.

Link to Tordon® label.

PLEASE NOTE -The proper use and application of herbicides can be an effective way to control and eradicate noxious and invasive plants. Before using herbicides, always carefully follow the label and safety instructions on the label. While we recommend the use of herbicides as one of the effective tools for integrated pest management, the Idaho Weed Awareness Campaign assumes no liability for herbicide applications.

For more information, click on the link below to download the Idaho's Noxious Weeds Control Guidelines publication produced by the University of Idaho Extension.

U of I Idaho's Noxious Weeds Control Guidelines (183 KB PDF download)

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Grazing Programs - Goat & sheep are able to digest leafy spurge and are effective in preventing this weed from spreading from season to season through effective grazing programs.

BiocontrolBiological Control - A biological control agent has been USDA approved and is effective in controlling leafy spurge. To collect or purchase insects, contact your county weed superintendent which can be found on this website or under County Government in the phone book.

Approved biological control agents for Leafy Spurge:

  • Aphthona czwalinae, the black leafy spurge flea beetle, does well in continental climates with warm and dry summers and sites with relatively high humidity and mesic, loamy soils where the host plant is growing with other vegetation. This agent is established in Idaho and surrounding states and has shown to effectively reduce cover, density, and biomass 3 – 5 years post-release. This agent can be collected from mid-June through July.
  • Aphthona flava, the copper leafy spurge flea beetle, is well established in Idaho and surrounding areas and does well in areas that are sunny and without clay or acidic soils. This agent is effective once established, reducing plant densities dramatically. A. flava can be collected from June through mid-August. As with other Aphthona species, larvae feed on the root hairs of leafy spurge while adults feed on leaves and flowers.
  • Aphthona lacertosa, the brown-legged leafy spurge flea beetle, is destructive in the larval and adult stages. This species is established in Idaho and surrounding states. Adults are collected from early summer through July. Redistribution efforts should concentrate on open, sunny, mesic sites.
  • Aphthona nigriscutis, the black dot leafy spurge flea beetle, is established in Idaho and surround states. It is destructive in the larval and adult forms and best suited to dry sites with maximum solar exposure where ant and/or grasshopper populations are minimal. This species can be collected from June through August.
  • Hyles euphorbiae, the leafy spurge hawk moth, is established in Idaho and surrounding states. This agent is ineffective as a biological control agent as the larvae feed on leaves and bracts of leafy spurge without causing mortality. The larvae can be collected from plants in July and September or the adults can be collected using sweep nets and a black light.
  • Oberea erythrocephala, the red-headed leafy spurge stem borer, damages leafy spurge plants in the adult and larval life stages. Adults girdle the stem of the plant when ovipositing and the larvae mine down the stem and feed in the crown and root system. Larval galleries may allow pathogenic fungi to enter the roots as well. Plants with stem diameters in excess of 3.0 mm are necessary in addition to with riparian areas with trees. This agent is established in Idaho and surrounding states. Adults can be hand-picked in the morning before they become too active.
  • Spurgia esulae, the leafy spurge tip gall midge, is destructive in the larval stage, attacking the growing tips of leafy spurge plants and destroying the shoot’s ability to flower and produce seeds. This agent is established in Idaho and surrounding states. To redistribute, galls containing mature larvae can be clipped, bunched, and wrapped in damp towels or damp cotton. They should be taken to the field as quickly as possible and placed upright in a wire frame or other device so that the larvae will not be found by ants and other predatory insects.

OTHER RESOURCES

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