TEAM Leafy Spurge: Working Together to Purge Spurge Summer 2000 Field Season

Data collection continued on several existing TLS projects, and program managers are especially pleased with the progress of multi-species grazing, grazing-biocontrol and biocontrol-herbicide demonstrations.

Multi-Year Projects
•Inventory & Assessment

•Multi-species Grazing, Grazing-Biocontrol

•Herbicides, Herbicides-Biocontrol; Integration of Emerging & Current Herbicide Technologies

•Soci-Economic Impacts

•Dietary Preferences of Different Sheep Breeds

•Ecological Barriers to Aphthona Flea Beetle Establishment

•Remote Sensing (GIS/GPS mapping); GIS Database; Early Detection System; Management Approach to Leafy Spurge

•Ecologically Based Support Decision Model

•Utilization of Oberea Erythrocephala

To sum it up, spurge reductions at multi-species grazing, grazing-biocontrol and herbicide biocontrol demonstration sites in the Sentinel Butte, N.D., area were dramatic. The sites, which have been established for just three years, are clearly showing that biologically based integrated pest management works and works well.

In addition to work on continuing projects, several new TLS projects were initiated in 2000.

Prairie Fringed Orchid: Two of the continent’s Prairie Fringed Orchidlargest remaining populations of the endangered prairie fringed orchid are being threatened by leafy spurge infestations. This demonstration, located at Sheyenne National Grasslands in southeastern North Dakota - where biocontrol generally does not work well because of wet, sandy soil - is showing how herbicides can be used to control leafy spurge without harming the orchid.

Native Euphorbias: Some native Euphorbias are classified as sensitive species, but no field data regarding host specificity of Aphthona spp. flea beetles on native spurges exists. This project has three objectives: 1) Identify native Euphorbias that may exist in the TLS study area; 2) Locate and map native Euphorbias in the TLS study area, inventory site characteristics and survey for presence of Aphthona spp. flea beetles; and 3) Release Aphthona spp. flea beetles at some sites to monitor flea beetle impact on non-target, native Euphorbias.

Impact of Grasshopper Control Tactics on Aphthona Flea Beetle Populations: A common question regarding leafy spurge biocontrol is, "Can I spray for grasshoppers without hurting my flea beetles?

Nelson Foster holding grasshopper tube
USDA-APHIS entomologist Nelson Foster’s project is designed to identify insecticides that will control grasshoppers while having the least amount of impact on flea beetles.

" This project will provide much needed answers. Several commonly used chemicals are being compared to quantify grasshopper control and flea beetle mortality, and to identify/investigate treatments that can effectively control grasshoppers while having the least amount of impact on flea beetle populations.

In addition, two projects that were initiated last year are generating considerable interest.

Dietary Preferences of Different Sheep Breeds: Results from the TLS multi-species grazing trial at the Sentinel Butte, N.D., demonstration site indicate significant dietary preferences for leafy spurge among different breeds of sheep. This research could potentially enable range managers to make breed recommendations specifically for leafy spurge control. In addition, data provided by the study could lead to a better understanding of how leafy spurge is metabolized, which could potentially be used to increase leafy spurge consumption by sheep.

assistant measuring vegetation
at a grassland site
A USGS-BRD research assistant measures vegetation at a grassland bird nesting study site in the Sheyenne National Grasslands.

Effects of Leafy Spurge on Nesting Grassland Birds: This U.S. Geological Service-Biological Resources Division project is designed to evaluate the impact of leafy spurge infestations on grassland-dependent birds in the Sheyenne National Grasslands. Preliminary data indicates that some species are less common in heavily infested areas, and that fewer nests are present. Although not directly related to leafy spurge control, this project can potentially provide valuable information for resource managers. Grasslands birds have shown greater populations declines during the past 30 years than any other group of bird, and are of particular concern to the conservation community. Knowing if and how leafy spurge affects grassland birds in particular, and biodiversity in general, will help resource managers make intelligent, informed decisions regarding resource allocation for leafy spurge and noxious weed management. In addition, the project can potentially bring new players into the war on noxious weeds.

Researchers are continuing with efforts to find new biocontrol agents for leafy spurge, and are focusing efforts on agents that originate from (and are thus well adapted to) cold, wet climates. Host specificity testing is now being conducted on four "new" species of Aphthona flea beetles: A. nigriscutis, A. russica, A. chinchihi and A. abdominalis.

Researchers are particularly optimistic about the nigriscutis and russica spp. Nigriscutis colonies now established in the U.S. were originally obtained from dry, moderately cold climates in Hungary; the "new" strain was collected from colder, wetter climates in Russia and will hopefully have a broader range of tolerances. A. russica also shows promise as an agent that can establish quickly and is quite aggressive towards spurge.

Another potential agent, Thamnurgus euphorbiae, a stem feeding beetle, suffered a setback in host specificity testing when it was shown to feed on Euphorbia inundata, which serves as a substitute for the federally threatened E. telephioides.

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