With the object of developing a test method to determine the effectiveness of wood preservatives against soft rot attack, tests have been carried out with pure fungal cultures using vermiculite as the substrate for untreated and preservative impregnated wood blocks. In these tests the suitability of common commercial, simple disposable beakers was proved successful as a substitute for the glass bottles used up till now. Comparing the traditional wide-necked bottles with the disposable beakers as test containers for beech and pine sapwood, in the beakers the extent of the wood decay in the beech was 20 to 99 per cent higher than it was using bottles. With pine sapwood in the beakers some values were smaller, some higher than with bottles, altogether the values seemed only negligibly higher using beakers rather than bottles. Tests were carried out to determine the effectiveness against soft rot attack of a copper/chrome/fluorine and a fluorine/chrome/arsenic preservative respectively. In both test series the wood decay caused by individual test fungi or mixed fungal cultures was compared with that caused by the natural microflora of the test soils. In the tests with a copper/chrome/fluorine preservative distinctly higher weight losses were produced in beech blocks in vermiculite by the microflora of the test soil than by particular soft rot fungi. In contrast the tests with the pine sapwood blocks showed practically no difference. The toxic limits determined with individual fungi correspond with those values quoted in the literature for soil burial tests. Also in the tests with a fluorine/chrome/arsenic preservative the pine sapwood blocks used were more severely attacked by the microflora of the test soils than by particular fungi. The toxic values against soft rot attack were of the same order as determined 10 years ago in spite of the use of a different type of soil.

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