6 Wood Discoloration

210 8 Habitat of Wood Fungi
timber and outside doors by blue-stain fungi and molding in damp rooms
(Chap. 6) (Frössel 2003; Hankammer and Lorenz 2003).
The common house-rot fungi are serious wood decayers. Among them, S.
lacrymans is considered in Europe as most dangerous and most hardly controllable
fungus due to its ability to transport nutrients and water. Traditionally, it
is also supposed to possess some further specific features, which, however, do
not all stand up to laboratory results. Nevertheless, in Germany, S. lacrymans
has to be clearly differentiated from the other house-rot fungi in view of refurbishment.Morefar-reachingmeasureshavetobeperformedinthecaseofits
presence. Thus species identity should be known.
For identification, fruit bodies are preferentially used (Grosser 1985; Breitenbach
and Kränzlin 1986; Jahn 1990; Ryvarden and Gilbertson 1993, 1994;
Krieglsteiner 2000; Weiß et al. 2000; Kempe 2003; Bravery et al. 2003). A diagnostic
key for fungi on structural timbers based on their fruit bodies is
available in the internet and is to be completed in time (Huckfeldt 2002).
Some species only rarely fructify in buildings, or after isolation in laboratory
culture, or do it never. However, some house-rot fungi form mycelial strands
(cords). The classical strand diagnosis from Falck (1912) is old and includes
only a few species. A diagnostic key including color photographs based on
measurements in infected buildings and on wood samples in laboratory culture
comprises several species (Huckfeldt and Schmidt 2004, 2006). An updated
version is shown in Appendix 1. A recent textbook comprises photographs and
identification keys for fruit bodies and strands of fungi occurring on wood in
indoor and exterior use (Huckfeldt and Schmidt 2005).
If neither fruit bodies nor strands, but only vegetative mycelia are present,
e.g., if only mycelium is found in buildings, or as it is the case for fungi cultured
in the laboratory on agar, there are keys and books for mycelia (Nobles
1965; Stalpers 1978; Lombard and Chamuris 1990). However, some genera
among the house-rot fungi are hardly or not at all distinguishable into species,
like Antrodia, Coniophora and Leucogyrophana. Thus, molecular methods
may be used (Chap. 2.4.2). Among the DNA-based techniques, species-specific
ITS-PCR differentiated seven indoor wood-decay Basidiomycetes (Fig. 2.23,
Table 2.9; Moreth and Schmidt 2000). The technique is meanwhile used in
Germany for commercial identification of house-rot fungi. Sequencing of the
internal transcribed spacer (ITS) of the ribosomal DNA (rDNA) and subsequent
sequence comparison by BLAST with ITS sequences from correctly
identified fungi deposited in the nucleotide databases is to date the best
molecular tool for diagnosis (Table 2.8 and Fig. 2.22; Schmidt and Moreth
2002, 2003).
There is a great number of investigations on the physiology of house-rot
fungi in text books (e.g., Jennings and Bravery 1991), monographs (e.g., Cockcroft
1981), and publications that may used in support of identification. Among
the physiological parameters, growth rate and reaction to wood moisture con-
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