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In 90 silver-firs from five Bavarian stands more than 30 crown and stem characteristics were considered and quantified in an experiment. Trees affected by fir-dying, show, as a rule, the following combinations of characteristics. The mean number of needle age classes is strikingly low, the length of the green crown and its relation to the total length of the stem is especially weak. They possess a pathological wetwood. A positive peroxidase reaction gives evidence that it is colonized by wood destroying microorganisms.

The fresh inner bark of Norway spruce sterns and roots inhibits mycelium growth of Fames annosus on malt agar. Nearly all fungistatic substances of the inner bark can be extracted with chloroform and acetone. The acetone-soluble fraction, which amounts to 13-27% of bark dry matter, was analysed. Up to now 12 phenolic substances have been identified, 5 of them have proved to inhibit Fomes annosus in vitro. Open-air-experiments showed, that desiccation of the root-zone, manganese deficiency and nitrogen hypertrophy decrease the inhibitory effect of the inner bark as well as its content of fungistatic substances. The degree of heart rot attack in older spruce stands was found to be negatively correlated with the N-, Fe- and Mn-concentrations in needles.