Charles R. Krause, Richard C. Derksen, LeonaE. Horst, Ross D. Brazee, Michael G. Klein, and MichaelE. Reding, U.S. Department of Agriculture, Agricultural Research Service, Application Technology Research Unit, Ohio Agricultural Research and Development Center (OARDC), The Ohio State University, Wooster, Ohio; Randall Zondag, Ohio State University Extension, Lake County.
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| Figure 3. A portable meteorological station was installed within the experimental plot. |
During the 2002 growing season, little apple scab disease was observed macroscopically. Free moisture on leaf surfaces was lacking, as recorded by the meteorological station, indicating conditions were not conducive for disease development.
Electron beam analysis of leaf samples observed during the early portion of the year (2002) confirmed the lack of the fungal pathogen. When limited disease (< 5% to 10%) occurred on both cultivars in June 2002, EBA confirmed the presence of the pathogen. While fungicide coverage was measured with EBA, low disease pressure did not permit quantifying differences in efficacy.
This project involved development of experimental methods, including the use of remote leaf wetness sensors, essential for studies of apple scab. The use of fungicides as tracers for EBA was developed as part of the analytical protocol for studying spray efficacy. Specimen handling technology was developed for subsequent studies. Techniques developed in this study will be adapted for assessment of other disease and pest management problems. Improved knowledge of the basis of efficacy and coverage will improve grower profitability and protect farm workers, consumers, and the environment.