Phytopathogenic Bacteria Associated with Bacterioses of Common Oak (Quercus robur L.) in Ukraine

Studying the biological characteristics of the causative agents of bacteriosis of the common oak (Quercus robur L.) (to highlight the links between the key factors of pathogenesis and bacterial groups) is a new and relevant area of research. This work aims to identify the species composition of phytopathogenic bacteria associated with common oak bacteriosis and to study the morphological, cultural, and biochemical properties of pathogens. To establish the general phytosanitary state of the surveyed stands, classical forest inventory and phytopathological (visual on based on typical symptoms of the disease and macroscopic) methods were used. The properties of isolated bacteria were studied using microbiological methods. The weakening and dieback of common oak in the forests of Ukraine is directly related to four types of bacterioses and their pathogens: the soft bacterial rot of acorns (Pectobacterium carotovorum subsp. carotovorum, bacterial wetwood (Lelliottia nimipressuralis), dry rot of branches and trunks (Erwinia rhapontici), and canker disease (Pseudomonas fluorescens and Pseudomonas sp.). Research on the correspondence between the biological properties of common oak bacteriosis pathogens has established that the synthesis of pectin-degrading enzymes and the ability to ferment with the release of acid and gas in many carbohydrate media by phytopathogenic bacteria is the main characteristic. This ensures the intensity and typical symptoms of the pathogenesis of a particular bacteriosis.