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Ecology and Epidemiology

Isolation of Erwinia amylovora Bacteriophage from Aerial Parts of Apple Trees. D. F. Ritchie, Graduate Assistant, Department of Botany and Plant Pathology, Michigan State University, East Lansing, MI 48824; E. J. Klos, Professor, Department of Botany and Plant Pathology, Michigan State University, East Lansing, MI 48824. Phytopathology 67:101-104. Accepted for publication 16 August 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-101.

Populations of Erwinia amylovora bacteriophage greater than 10⁶ plaque-forming units (PFU) per gram of tissue were isolated without enrichment from diseased aerial parts of apple trees during the summer of 1975. Three phage isolates were selected from different geographical locations. Two types of plaques were produced; a clear-centered plaque with a spreading translucent halo and a smaller plaque without a halo. Thirty-five bacterial isolates, consisting of nine genera, 18 species, and 15 strains of E. amylovora were typed; the phages lysed only E. amylovora. The burst size of the three isolates was 40 to 50 PFU per cell. The phages could be stored at 4 C and –20 C but lost titer when stored at 24 C.