Incidence of ash dieback in the Left-Bank Forest-Steppe depending on stand characteristics

V L Borysova,V L Meshkova

doi:10.33220/1026-3365.136.2020.157

Abstract

The incidence of ash dieback in the forest-steppe part of Sumy and Kharkiv Regions was analysed taking into account the type of forest site conditions, the stand age, relative stocking density, site index class and the proportion of European ash in the stand composition. Ash dieback is quite widespread in inspected stands of the Left-Bank Forest-Steppe of Sumy and Kharkiv Regions. The disease spreads similarly in natural and artificial stands. It was more often revealed in the fresh fertile forest site conditions, however, such forest site conditions are the most spread and the most favourable for European ash. It was found that ash dieback incidence tends to grow with a stand aging and lasts up to the stand’s age of 80. It can be explained by the development of stem and collar rots which occur later. Ash dieback incidence is the highest in the stands with 40–70 % of ash in their composition, at a relative density of stocking over 0.5 in the stands of different site index classes.

Highlights

European ash (Fraxinus excelsior L.) is currently threatened across most of its distributional range by ash dieback caused by Hymenoscyphus fraxineus (Baral et al 2014)
The analysis revealed the ash dieback symptoms in 47.9% of subcompartments of plantations and 52.1% in the natural stands in Sumy Region
In Sumy Region, most of the inspected ash stands (98.1 %) and dieback symptomatic ash stands are in the fresh fertile forest site conditions

Summary

Introduction

European ash (Fraxinus excelsior L.) is currently threatened across most of its distributional range by ash dieback caused by Hymenoscyphus fraxineus (Baral et al 2014). In eastern Ukraine, the ash decline symptoms were observed for the first time in 2010 and the H. fraxineus was detected in symptomatic shoots in 2012 (Davydenko et al 2013). The disease results in both a premature death of trees and stands, and deterioration of wood quality (Metzler et al 2012, Langer 2017). The disease is characterized by a rapid gradual dieback of ash crowns during the growing season. The symptoms of the disease are necrotic spots on the bark of shoots, discoloration of wood and leaves, necrosis of leaves, a premature leaf fall, necrosis of the trunk, death of shoots and water shoots (Fig. 1)

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