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Abstract: The term saprophagous, meaning here feeding on bacteria and small particles of organic matter, would cover many hundreds of species of nematodes, mostly in the order Rhabditida. The almost inevitable occurrence of these nematodes in mushroom beds is well known. However, because of the selectivity of this substrate, the number of species which commonly occur in them is restricted (Hesling, 1979) but still considerable. Because these nematodes are almost always present, it is not surprising that, when yields are low for no other apparent reason, saprophagous nematodes have been implicated. Hesling (1979) summed up the experimental evidence suggesting detrimental effects of saprophagous nematodes as "scanty and of doubtful validity". However, Ross and Burden (1980) have since provided new insights and results which should stimulate renewed investigation of the matter. Ross and Burden (1980) noted the following features of a crop failure induced by saprophagous nematodes: 1. There is a sudden drastic drop in production but with apparently normal spawn run up to the time of casing.2. Off-white strains are more severely affected than white strains. 3. There is often a history of overwatering, watering at spawning being especially critical. 4. Non-productivie patches have high numbers of nematodes and normal patches low numbers. 5. Considerable numbers of nematodes have been introduced at spawning. 6. After a spawn run of 2 weeks infestation has little effect. 7. Infestation of casing is only important if spawn run is young. In Australia, Blake and Conroy (1959) drew attention to the widespread occurrence of both mycophagous and saprophagous nematodes in outdoor ridge beds which were the main form of culture at that time. With the change away from ridge beds, mycophagous nematodes have become an infrequent problem but saprophagous nematodes are almost always found in compost samples from cropping beds. Cases of sudden steep drops in production with characteristics 4 and 5 above occur from time to time. These usually occur in mid to late summer and severe cases have been noted with white strains. In this paper we report experiments which investigated the effects on cropping of saprophagous nematodes from local mushroom beds.
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