H-Mutant Phage Control of Harmful Plant Bacteria

Bacterial plant diseases of economically important crops are difficult to control. Chemicals used to treat bacterial plant diseases cannot only alter soil flora and auna, but ar unreliable for preventive control when environmental conditions favor growth of plant pathogenic bacteria. This research is directed toward development of an effective control for bacterial plant diseases using phages which are specific for their bacterial hosts. Although the use of phages against bacterial plant pathogens has been proposed in the past, no commercial application has taken place. This was due largely to the development of mutant bacteria resistant to the controlling phage. Unlike past uses of a single phage for treatment, this method utilizes a mixture of phages including h- or host-range mutants. H-mutants, derived by spontaneous mutation of the wild-type parent phages, will attack and kill not only phage-resistant mutants but also wild-type bacteria. It is proposed that mixtures of phages, containing h-mutants, can be used effectively to control pathogenic bacteria which cause a variety of plant diseases as well as to control ice nucleation.