Within diploma thesis was processed the issue, which is solving the wasting of ashes in selected plants LS Strážske. The contents is given bionomics of fungus Chalara fraxinea, secondary harmful factors and their influence on ashed plants. Research of model areas was evaluated the incidence of wasting ashes on forest ecosystems and then were sugested preventative measures against another extension of diseases. In thesis is described activation of Hylesinus fraxini, which has over-multiplied and has started to attack ashes plants not only in Slovak, but also in Europe. There was evaluated a change of colour, loss of leaves in ashed plants and near catchers and also damage on catchers. Within these observations in terrain was found, that ashed plants wasting more and more every year. In model areas was identified, that Hylesinus fraxini and Chalara fraxinea have a great influence on the loss of leaves, it leads to faster wasting of trees and also to disappearance of European ash from our forest.