The Influence of the Concomitant Microflora on Establishment and Dieback of Decay Fungi in Standing Timber

The microbiological aspects that designate development of decay in standing timber were assessed by determining the resistance to succession as well as the competitive saprophytic ability (kratovirulence, KV) of 40 species of wood destroying basidiomycetous fungi (WBF), proved to be members of 7 ecological categories. The categories (i) to (iv) comprise predominantly pathogenic WBF (pathogens) with high pathovirulence (PV) and correspondingly low KV properties that are dominant in the decay of standing timber. The categories (v) to (vii) include saprophytic WBF (saprophytes) with occasional or no PV and increasingly dominant KV properties which are native to slash and plant residues. On sterilely overgrown blocks of fertilized wood meal which had been exposed to airborne contaminants, most pathogens displayed the same degree of resistance to the insinuation of successive microbes as did the saprophytes. In the inoculation attempts of randomly contaminated wood meal, however, the low‐kratovirulence, pathogens were unable to repress the multitude of the antagonistic resident microorganisms in order to establish themselves in this substrate. In contrast, most high‐kratovirulence saprophytes reduced the number of, or completely eliminated, these antagonistic resident microorganisms in wood meal to create the preconditions for colonizing this substrate themselves for up to 1,200 days. In application of these results to the conditions in standing timber it is concluded that the wounded living tree involuntarily promotes the entry of a pathogenic WBF by keeping its natural antagonists down. The once established WBF can then protect its vegetative thallus itself from being overgrown by successive microbes.