UTILIZING UVR PROTECTANTS TO OPTIMIZE BACTERIOPHAGE FOR FIRE BLIGHT MANAGEMENT By Madison Dobbins Erwinia amylovora is a devastating bacterial pathogen that is the causal agent of the pome fruit disease fire blight. For plant diseases, alternate biological controls, such as bacteriophage, are now the subject of many research studies as a potential substitute for the use of antibiotics. In several in vitro studies, bacteriophage have been shown to reduce the survival of E. amylovora; however, for field application, protection from degradation by ultraviolet radiation (UVR) is required. We examined if the addition of peptone or carrot juice, both highly pigmented liquids, and kaolinite clay could protect individual E. amylovora bacteriophage from inactivation by UVR. We studied the effects of these potential protectants to bacteriophage survival following dosing with UVR wavelengths in the UVA, UVB, and UVC range. We found that additives of either peptone or kaolinite clay acted as UV-protectants. Greater concentrations of both the peptone and kaolinite clay demonstrated greater protective qualities against UVR. In a field study, commercial bacteriophage cocktails such as Agriphage, Firequencher A and B, cocktails of E. Amylovora specific bacteriophage, were also used to demonstrate the protective qualities of additives, as well as the potential for bacteriophage to be used more regularly as a biological control agent against E. amylovora. These field studies identified three separate bacteriophage - the Agriphage cocktail (Certis and Omnylytics), Φ31 -3 and Φ21-4 - as potential protectants against the occurrence of E. amylovora.
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