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Grazing Research & Demonstration -- Maus Study Site, Sentinel Butte, ND & South Fork of Moreau River Site in SD

 Scott Kronberg

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

The major problems or issues being resolved are to determine if specific breeds of sheep graze leafy spurge more readily than other breeds and to determine if sheep grazing of leafy spurge can compliment flea beetles and a herbicide for improved long-term control of leafy spurge. During the summers of 1999 and 2000, four common breeds of sheep were grazed on pastures with heavy infestations of leafy spurge (Maus Study Site) and the percentage of leafy spurge in their diets is being compared. For 2000, estimates of forage intake by all sheep while they grazed the spurge- infested pastures are being made so that the actual amount of leafy spurge consumed by individuals of each breed can be estimated. This should be useful information given that these breeds of sheep vary considerably in body size. Sheep were grazed on spurge-infested pastures at the study site at the South Fork of the Moreau River in 2000. Sheep exclosures are located within these pastures to allow for comparison of long-term leafy spurge control using a herbicide or flea beetles with or without sheep grazing.

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

Sheep grazing is a recommended method for leafy spurge control yet variation in the degree that sheep will graze leafy spurge has been reported. One reason for this variation is that there are differences among sheep breeds in respect to their preference for leafy spurge. If differences exist, then breeds with greater preference for leafy spurge should be identified so that managers can use this information if they wish to optimize leafy spurge control with sheep. Research in North Dakota indicates that combining grazing of leafy spurge with herbicide treatment improves leafy spurge control. Given the severe impact of leafy spurge on the northern Great Plains, improvements in its control with combined treatments in clearly advantageous. This is the same rationale for testing the impact on leafy spurge when sheep grazing is combined with flea beetles.

Question 3. How does it relate to the National Program(s) and National Program Component(s)?

The TEAM Leafy Spurge Project is 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 was your most significant accomplishment this past year?

The major problems or issues being resolved are to determine if specific breeds of sheep graze leafy spurge more readily than other breeds and to determine if sheep grazing of leafy spurge can compliment flea beetles and a herbicide for improved long-term control of leafy spurge. During the summers of 1999 and 2000, four common breeds of sheep were grazed on pastures with heavy infestations of leafy spurge at Sentinel Butte, ND and the percentage of leafy spurge in their diets is being compared. Our most significant accomplishment this year was to complete sample and data analysis for the 1999 grazing trial that gave us estimates of the percent of leafy spurge in the diets of the four breeds of sheep, and to conduct a similar trial in 2000 that will allow us to determine (when sample and data analysis is completed) if the preference of these four common breeds of sheep for leafy spurge is consistent from year to year. We expect to transfer information about the advantage (or lack thereof) of using specific breeds of sheep for optimal leafy spurge control with sheep to interested ranchers and land managers

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

Major accomplishments over the life of the project to date include: 1) determining that fertilizing leafy spurge-infested rangeland with nitrogen did not increase the palatability of leafy spurge to cattle and sheep (by decreasing its toxicity to them) and can not be recommended as a technique to aid in controlling leafy spurge, and 2) determining that during the seven weeks in which the four breeds of sheep were sampled for the 1999 trial, there were significant differences among the breeds in respect to the percentage of leafy spurge in their diets. If similar results are observed for the 2000 grazing trial, then specific breeds of sheep would be recommended for optimal spurge control.

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

Over the next year we will finish our sample and data analysis for leafy spurge preference by four common breeds of sheep and make recommendations as to whether or not one or more breeds are preferable for use in controlling spurge. In the next year or two, we will publish the results from this study in scientific and lay articles and publish the results of the spurge fertilization study in a scientific journal. Over the next two years, we will continue our evaluation of the effectiveness of combining leafy spurge control treatments (herbicide treatment plus sheep grazing and flea beetles plus sheep grazing), and we will complete a study to determine if wild rodent and/or ungulate species are dispersing leafy spurge seed into previously non-infested areas.

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?

No science or technologies have been transferred to date, but we expect to do so in the next two years. We expect to transfer information about the advantage (or lack thereof) of using specific breeds of sheep for optimal leafy spurge control with sheep to interested ranchers and land managers during the next year. The primary constraint to adopting this technology could be the cost of acquiring sheep of a specific breeding and potentially other drawbacks (e.g., less valuable wool or lower lamb production) associated with switching to a breed of sheep that has greater preference for leafy spurge (if in fact there are consistent breed differences). If other sheep-related factors (e.g., reproductive status, years of experience grazing leafy spurge) turn out to have a greater effect on spurge preference, then simply using a specific breed of sheep in attempting to obtain optimal spurge control would have limited durability.

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 (NOTE: this does not replace your peer-reviewed publications which are listed below).

Cover article titled Leafy spurge: no silver bullet by Mary Brashier in Farm and Home Research 2000, 51:10-13 (popular press magazine from SDSU College of Agriculture and Biological Sciences and Agriculture Experiment Station)

Question 9. Scientific publications

None.

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