Some biological properties of phytopathogenic strains of Pseudomonas sp., that cause new bacterial disease of the linden (Tilia sp.) were studied. It is known that such properties as plasmid availability and production of bacteriocinogenic substances in many cases relate directly or indirectly to the pathogenesis mechanisms. Therefore, the study on these properties often gives a possibility to make certain suggestions about the latter and further investigation. All pathogenic isolates tested were revealed to have plasmid DNA with the same electrophoretic mobility, being resistant to a high dose of antibiotics of different types, and to produce bacteriocinogenic substance(s).