Symptoms and etiology of dieback of silver fir (fir dying). I. Evaluation of disease symptoms. The percentage of dead crown and the intensity of "stork's-nest" formation, expressed as a shoot length ratio, are disease symptoms more objective and easier to handle than the degree of needle retention.In silver firs, a normal wetwood core must be distinguished from a pathological one. Only the latter forms part of the silver fir diehack syndrome. Frequently a net oi Armillaria rhizomorphs is found in the root systems of diseased trees, sometimes down to 1.5 m.

The effect of water extracts of leaf and needle litter from different forest trees on the mycelial growth and the germination rate of conidia of Fomes annosus (Fr.) Cke. Litter extracts from various forest trees and stands have distinct effects on mycelial growth and germination rate of conidia of Fomes annosus. The effects depend on concentration of the extract, period of extraction and on date of collecting the litter samples.