Bacterial ulcer — a dangerous disease of horse chestnut in Europe

Abstract

Goal. To analyze and summarize the data of harmfulness, methods of distribution, identification, and methods of control of the causative agent of bacterial ulcer of horse chestnut Pseudomonas syringae pv. aesculi (Young, Bradbury, Davis, Dickey, Ercolani, Hayward & Vidaver 1991a) and predict the possibility of introduction of this species in Ukraine. Methods. General scientific — for generalization, comparison, and system analysis; field — for visual inspection of street horse chestnut plantations. Results. The causative agent of P. syringae pv. aesculi came to Europe from India and as a result of adaptation to the climatic conditions of the European continent became more aggressive. The main symptom of the lesion is weeping necrosis on the trunk and main branches. Horse chestnut trees affected by this pathogen often die within 3–4 years. Identification of the pathogen can be done by amplification and sequencing of the gyr B gene. A common pest of chestnuts in Europe and Ukraine — chestnut moth, leads to greater damage to trees by bacterial ulcers, but the possibility of the pest to be a vector of P. syringae pv. aesculi not confirmed. The source of infection can be epiphytic populations of the pathogen, which are on the leaves and bark of horse chestnut trees. In Kyiv, among the street plantations of horse chestnut, there are trees with typical for bacterial ulcers lesions of the trunk. To confirm the presence of the pathogen in Ukraine, it is necessary to monitor horse chestnut plantations in different areas and laboratory confirmation of the pathogen identification. Preventive measures should be taken to prevent the spread of the pathogen. Conclusions. Phytopathogenic bacteria P. syringae pv. aesculi affect horse chestnut in all European countries. The status of the pathogen for Ukraine has not been determined yet. A promising method of pathogen control is the introduction of resistant to P. syringae pv. aesculi forms of horse chestnut.