Most laboratory techniques for the determination of growth rate not only use a medium (agar) unrelated to practice, but also yield values that are often far less than those found in practice. Also, most laboratory techniques for the determination of decay capacity ensure that the whole of a small test block becomes fully surface-colonised within the first few days; whereas in Australian practice Serpula lacrymans most often grows in one direction, from the walls across floorboards, with resulting collapse first evident near the ends of boards adjacent to that wall. This paper reports on a new, medium-scale, laboratory technique enabling growth rate measurements and (subsequently) a decay capacity measurement, all using the same piece of timber. Eight strains of Serpula lacrymans have been used in the three evaluation experiments carried out to date. Mean values for growth rate on wood have been suitably high, probably as high as for the most favourable practical situations. Resulting mass losses have, as was intended, been reduced in comparison with values previously obtained in small-scale techniques. This direct technique has confirmed the conclusions that others have made based on their comparisons; that it seems unlikely that the pattern of differences between growth rates of different strains has any consistent similarity with their corresponding decay capacities.

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