Relationship of necrotic disease of beech trunks to the sociological position of trees in the stand

The authors analyse the results of investigations into the degree of necrotic damage of beech bark carried out in the whole territory of the Slovak Republic. The aim of these analyses is to answer a question about the relationship between the degree of necrotic damage of beech trunks and sociological position of trees in the stands studied. In the years 1995-2001, the degree of necrotic damage by tracheomycotic type to 6,579 beech trunks was evaluated in 54 selected localities in 33 orographic units. The lowest frequency (4.3%) of trees showing the 3 rd and 4 th degree of necrotic damage was found in the 1 st tree age class. The frequen- cy of damaged trees increased proportionally with the worsening sociological position of trees. The values of the index of trunk necrotisation (I NK ) increased from 0.71 in the 1 st tree age class to 2.14 in the 5 th tree age class. It also corresponded with dynamics of disease frequency in the tree age classes. The authors found that the extent of necrotic disease of beech trunks expressed by I NK was signifi cantly infl uenced by the sociological position of individual trees in the stand. They conclude that strongly infected trees of the 4 th and 5 th tree age class left in the stands is problematic from the phytopathological point of view. Such trees left in the stands may cause a serious epiphytotic because these trees are one of the infection sources ot the necrotic disease.