Tuberculosis Pathology of Fraxinus Excelsior L. in Ukraine: Symptomatology, Etiology, Pathogenesis

Anatoly Goychuk,Maryna Shvets,Ivanna Kulbanska

doi:10.48077/scihor.24(5).2021.69-80

Abstract

Given the forestry, the ecological and economic value of forests with the participation of Fraxinus excelsior and taking into account the intensive deterioration of their phytosanitary status in modern conditions, a comprehensive study of symptoms, causes, and pathogenesis of ash tuberculosis with further development of effective protection measures, including using biological products based on Bacillus sp. and other myco- and microorganisms, is a particularly relevant area of research. The aim of the research is to identify negative abiotic and biotic factors in the pathology of F. excelsior. In the process of research general scientific and special research methods were used (microbiological, mycological, phytopathological, entomological, and silvicultural-ecological methods). It is emphasized that the pathology of the common ash is a multifaceted phenomenon with interrelated processes of infectious and non-infectious nature, which in recent years has led to epiphytic dieback and now has a tendency to increase. It has been established that tuberculosis of F. excelsior is the most common and harmful disease within the study region and causes more economic than environmental damage. Bacteria of the genera Pseudomonas sp., Erwinia sp., and Xanthomonas sp., as well as micromycetes, which mainly take the place of the concomitant mycobiota. There are five stages (phases) of the development of tuberculosis pathology, which differ significantly in symptoms. The species composition of harmful insects has been identified. It is shown that hydrothermal stress is a catalyst for the epiphytic dieback of common ash. Direct dependence of the spread of tuberculosis on the share of ash in the stands of different age groups was revealed. In the study area, tuberculosis reaches epiphytotics on F. excelsior, especially at a young age. The expediency of distinguishing the causes and pathological processes associated with ash tuberculosis is indicated, so as not to confuse the disease-catalyzing factors and the factors that lead to the complete degradation of ash stands

Highlights

It is established that a peculiar trigger of the pathological process and genesis of the disease is a set of factors of synoptic nature and as a consequence of dysfunction of immune structures, with obvious manifestation and implementation of ecological and trophic niches of phytopathogens of fungal and bacterial etiology
The purpose of this study is to identify negative abiotic and biotic factors in the pathology of F. excelsior, to determine the microbiota on infected shoots, leaves, and buds of dieback stands, to establish the dependence of the spread of tuberculosis on the proportion of ash in the composition of stands of different age groups
The microbiota of infected shoots, leaves, and buds of dieback stands of Fraxinus excelsior is represented by a complex of pathogenic species of the genera Pseudomonas sp., Erwinia sp., Xanthomonas sp., Which are dispersedly localized in the affected area

Summary

Introduction

It is established that a peculiar trigger of the pathological process and genesis of the disease is a set of factors of synoptic nature and as a consequence of dysfunction of immune structures, with obvious manifestation and implementation of ecological and trophic niches of phytopathogens of fungal and bacterial etiology. According to the authors' research, the formation of neoplasms instead of ordinary inflorescences on common ash trees is associated exclusively with bacterial etiology, including the causative agent of ash tuberculosis – Pseudomonas syringae pv. Phytoparasitic nematodes have a harmful effect on trees of the genus Fraxinus. Most often noted by researchers on Fraxinus americana – Meloidogyne sp. Macrodorum, Ditylenchus sp., Gracilacus audriellus, Helicotylenchus sp., H. playturus, Hemicycliophora sp., H. gigas, Hoplolaimus sp., Longidorus sp, L. elongatus, Meloidogyne sp., M. ovalis, sp': Paratylenchus sp., Pratylenchus sp., P. crenatus, Rotylenchus sp., Trichodorus sp., T. aequalis, Tylenchorhynchus sp., Xiphinema sp., X. americanum, X. Chambersi; on Fraxinus excelsior – Helicotylenchus paxilli, H. varicaudatus, Pratylenchus penetrans; on Fraxinus mandschurica – Meloidogyne sp.; on Fraxinus nigra – Meloidogyne sp.; on Fraxinus pensylvanica – Criconemoides curvatum, Xiphinema americanum; on Fraxinus syriaca – Meloidogyne javanica; on Fraxinus velutina – Meloidogyne sp. Modern studies of the nematocomplex of ash trees indicate a particular danger from the species Bursaphelenchus crenati [3]

Objectives

Methods

Findings

Conclusion