Phenotypical Characteristics of Walnut's (Juglans sp.) Bacterial Diseases Agent

As known, walnut is vulnerable to various pathogenic microorganisms, in particular bacteria that can cause significant lesions during their cultivation. Over the last decade, causative agents of walnut's bacterial diseases, which previously did not affect this culture, have been discovered all over the world. The expansion of the spectrum of pathogens that can potentially affect walnuts can be associated with intense anthropogenic influence on the environment, changes in climatic conditions, globalization of the agricultural sector, and the selection of new varieties with a low content of tannins and alkaloids. The purpose of the work is a comparative analysis of a complex of phenotype features of collection and isolated ‘/strains to identify the latter. Methods. Classic microbiological, API-testing, phytopathological, and biochemical methods were used in the research. Results. Strains of phytopathogenic bacteria were isolated from affected walnut tissues in pure culture and analyzed for a complex of morphological-cultural, physiological-biochemical, and pathogenic properties. All isolated strains are capable of infecting a certain set of indicator (carrot and popato explants, beans, tobacco) plants and host (walnut's) plants, have a stable biochemical profile, and are significantly related to representatives of Agrobacterium tumefaciens, Xanthomonas arboricola, and Pseudomonas syringae species. In the fatty acid profiles of isolated strains, there was detected a typical representative of species Agrobacterium tumefaciens, Xanthomonas arboricola, Pseudomonas syringae set of fatty acids. Conclusions. The phenotypic properties of bacterial isolated and collected strains causing walnut diseases were analyzed and their similarity to representatives of Agrobacterium tumefaciens, Xanthomonas arboricola, and Pseudomonas syringae was established. It should be noted that walnut leaf spotting is caused by Pseudomonas syringae, which was discovered by us for the first time in Ukraine.