In this study, the characterization of several bacterial diseases affecting silver birch (Betula pendula Roth.), common ash (Fraxinus excelsior L.), white poplar (Populus alba L.), and white willow (Salix alba L.) in Ukraine were described. The typical symptoms, features of pathogenesis, and characteristics of the causative agents of the most common bacterial diseases of these tree species were shown. The following types of bacterioses were noted to be especially dangerous, namely, bacterial wetwood, fire blight, bacterial canker, and tuberculosis. Bacterial necrosis of the bark was a less dangerous disease. At the same time, all of the listed types of bacterioses were registered within the forest areas of the investigated region. The study revealed that bacterial wetwood of birch and poplar was caused by Lelliottia nimipressuralis; the bacterial canker of poplar is Pseudomonas syringae (Pseudomonas syringae f. populi and Pseudomonas cerasi); the fire poplar blight is caused by Pseudomonas cerasi (P. syringae); the common ash tuberculosis is caused by Pseudomonas syringae pv. savastanoi; and the bacterial wilt of the willow is caused by Brenneria salicis. The phenomenon of the introduction of microorganisms of different functional orientations as well as the formation of conditions for their activity in the rhizosphere of plants have been studied. In the future, it will provide the development of effective methods for the rapid identification of causative agents of bacterioses and plant protection measures based on multi-functional microbiological preparations based on highly effective strains of microorganisms.