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Assessment Project - Wyoming Component

Dave Kazmer


Question 1: What major problem or issue is being resolved and how are you resolving it?

Leafy spurge (Euphorbia esula) is an exotic perennial weed that infests over 5 million acres of grazing lands and wildlands in at least 29 states. As a part of The Ecological, Areawide Management (TEAM) - Leafy Spurge project, we are participating in a) a large-scale assessment of biological control agent releases on leafy spurge and b) remote sensing research to develop large-scale inventory methods.

Question 2: How serious is the problem? Why does it matter?

Economic impacts of leafy spurge infestations are estimated at $144 million annually in Montana, North Dakota, South Dakota and Wyoming alone. Environmental impacts include ground water contamination due to excessive herbicide use, greatly reduced plant species diversity in infested areas, and degradation of wildlife habitat.

Question 3: How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned?

The TEAM Leafy Spurge project is a part of the USDA/ARS Area-Wide Management Program. It is a component of Crop and Commodity Pest Biology, Control and Quarantine (304). TEAM Leafy Spurge complements efforts to develop new and improved pest control technologies and assess component technologies for integrated pest management (IPM) systems.

Question 4: What were the most significant accomplishments this past year?

a. Monitoring of vegetation and biological control agent densities was performed at the 109 long-term study sites in Crook County, Wyoming.

b. Remote sensing data including color and color-infrared imagery, Landsat TM satellite imagery, SPOT IV satellite imagery, and AVIRIS imagery were obtained or analyzed for the Wyoming study area. Ground reflectance data of leafy spurge, vegetation, soils, and other prominent features in the study area was also obtained in 1999. Ground truthing of the Wyoming study area was also done in June 1999.

c. Diagnostic DNA markers based on random amplified polymorphic DNA (RAPD) were developed to discriminate Aphthona nigriscutis from A. cyparissiae and A. lacertosa from A. czwalinae. These markers are being used to identify flea beetle species in 1998 and 1999 samples from all of the Assessment Project study sites in WY, MT, ND and SD.

Question 5: Describe the major accomplishments over the life of the project, including their predicted or actual impact.

In 1998 a study area in Crook County, Wyoming was selected about 5 miles west of Devil’s Tower National Monument. The area was characterized by topological position as upland, draw, or riparian. The vegetation was classified into three main types: woodland/grass, prairie/grass, and sagebrush/grass. Plots were established in each of the three topo position types, and also in each of the vegetation types (Table 1). Plots were also established in areas with aspects in each of the four cardinal directions. Plots were located in areas of extensive spurge, away from known releases, and in areas to expedite access. During May and June, 109 study plots were located and permanently marked in spurge infestations. Each plot location was also recorded using a GPS receiver. Vegetation measurements and flea beetle (Aphthona sp.) sampling were performed at each site. Six digital pictures were taken at each site including 5 pictures from an aerial perspective to document spurge cover and one site picture.

On June 25-26, 1998, flea beetles were released on 77 of the 109 sites (Table 1). Each of the 77 sites received 3,000 black flea beetles and 3,000 brown flea beetles.

In June and July of 1999, each of the 109 sites was revisited. Spurge and other vegetation cover were recorded and flea beetle sampling was performed. Methods used during the 1999 field season were the same as those described above for 1998. In addition, soil samples were also collected at 30 of the permanent sites. Flea beetles were recovered at most of the 1998 release sites and leafy spurge densities were noticeably reduced at a large proportion of these sites.

Prior to the 1999 field season, a Landsat TM image (7 bands, visible through MIR + thermal, 30 m pixel size) of the study area acquired on June 14, 1991 was used to perform an initial vegetation classification of the study area. This initial classification provided a ground-truthing and sampling framework prior to the 1999 field season and further acquisition of remotely sensed data in 1999. Aerial photographs taken near the peak flowering period were used in combination with orthophotoquads as additional remote sensing data and for verification of cover types in combination with field ground truthing. Both color and CIR aerial photos were taken in late June of 1998. The color photography was taken by Gerry Anderson (USDA, ARS, Sydney, MT) at a scale of 1:10,000. The CIR photography was taken by Horizon Air at a scale of 1:10,000. During 1999, 246 stratified (by vegetation type and presence or absence of spurge) random locations in the study area were visited on the ground. At each site the dominant vegetation type was recorded and the percent cover of leafy spurge was recorded. In addition, the presence of yellow sweet clover was noted.

A scene from the SPOT IV satellite (4 bands, G-R-NIR-MIR, 20 m pixel resolution) was acquired over the study area on July 7, 1999. From this imagery, spectral analysis techniques will be used to determine areas composed predominantly of leafy spurge. An Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) image was also acquired over the study area on July 6, 1999. With its hyperspectral capabilities, it provides the best resolution (spectrally, radiometrically, and spatially) for detecting leafy spurge.

During June of 1999, we also collected ground reflectance data of leafy spurge, vegetation, soils, and other prominent features in the study area. These spectra will be used as a “library” of known spectra in the image to perform spectral mixing analysis on the AVIRIS scene. The results from the AVIRIS data will be compared to results and accuracy assessments obtained from the SPOT image, the Landsat TM image, aerial photography and ground sampling.

Diagnostic DNA markers based on random amplified polymorphic DNA (RAPD) were developed to discriminate Aphthona nigriscutis from A. cyparissiae and A. lacertosa from A. czwalinae. These markers are being used to identify flea beetle species in 1998 and 1999 samples from all of the Assessment Project study sites in WY, MT, ND and SD.

Question 6: What do you expect to accomplish, year by year, over the next 3 years?

1. Continued monitoring of the 109 long-term study sites in Wyoming.
2. Further exploration of remote sensing as a tool for large-scale inventory of weed infestations and the large-scale impacts of weed management programs.

Question 7: What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?

Biological control agents were released on public and private lands in the first year of the project. The uncertain and slow impact of the current biological control agents for leafy spurge is the main barrier to broader adoption of this method.

Question 8: List your most important publications in the popular press (no abstracts) and presentations to non-scientific organizations and articles written about your work

None to date.

Question 9: Scientific Publications:
None to date.
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