Research problem being addressed and background:
Leafy spurge (Euphorbia esula) is an aggressive perennial weed that produces a milky latex sap irritating to cattle and humans. The deep root system of this non-native plant makes it very difficult to control by mechanical or chemical methods. While leafy spurge is primarily a range land weed, it occurs on Reclamation ditchbanks and rights-of-way. Weed control in these areas are heavily influenced by proximity to water, which restricts the use of certain herbicides. The resulting maintenance problems from the structural effects of the deep roots on the banks, safety issues due to skin and eye irritation from the plant's sap, and the need to avoid infesting neighboring agricultural fields and range land require action from Reclamation managers.
Most of our knowledge of biological control of leafy spurge comes from traditional biological control studies. These studies use square or circular study plots, however, Reclamation is concerned with leafy spurge in irrigation rights of way, which are narrow corridors. These corridors may serve as invasion routes for invasive species to spread either by water or by trucks and other vehicles. Reclamation needs to understand how biological control insects respond to such habitat and operational conditions.
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To test the feasibility of biological control of leafy spurge in the habitat conditions found along irrigation canal rights-of-way.
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Overall Outcome or Conclusions:
Conducted leafy spurge biocontrol studies at Garrison Diversion Water Conservancy District facility at Oakes, ND.
Found that numbers of insects that control leafy spurge are building to levels where they are beginning to have an effect on leafy spurge plant density. Insects generally move in a circular pattern out from where they are introduced. In these tests, they seemed to have moved well linearly along canal banks and rights of way in the area. Areas with very compacted clay soils show less insect biocontrol success than areas with deep soils which have ample plant root growth for beetle larvae to feed. It is anticipated that numbers of insects will reach a level in 2001 at which they will be harvested for redistribution to projects at additional sites.
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| Flea beetles on leafy spurge. |  |
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This irrigation canal right-of-way is bordered by agricultural land. As seen in the figure, this setting provides an invasion corridor for leafy spurge (yellow flowers). |
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Partners who participated in the project:
Bureau of Reclamation
- Great Plains Region
- Dakotas Area Office
- Office of Policy
Garrison Diversion Water Conservancy District
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Publications and/or Other Deliverables which have been provided during this fiscal year:
Summary in progress
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