At the previous meeting a new technique was presented that enables both fungal growth rate and wood decay rate to be measured using the same timber specimen. The technique (IRG/WP/1384) has previously been carried out with 1% malt as the sole nutrient within the small jar that provides the inoculum for this method. Results presented here relate to an additional level of 5% malt, with or without a nitrogen source in the form of ammonium sulphate at either 0.01 g or 1.0 g per litre. Two isolates of Serpula lacrymans (one of European and one of Australian origin) were used at a temperature setting of 20°C. The linear growth front was measured, on the 200 mm long specimens of Pinus radiata sapwood, between 10 and 21 days after the specimens were introduced to the inoculum. Mass loss values of these same specimens were determined after 12 weeks' exposure. Replication comprised three specimens, within each of three large jars, of each treatment. For both strains, increasing the malt level caused some reduction in growth rate, with the addition of nitrogen resulting in no further growth rate changes. In contrast, mass loss of timber was increased for both strains at the higher malt level. Furthermore, for each of the two malt levels tested, the mass loss due to both strains was further increased at the high nitrogen level.

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