Moulds in spawn-run compost and their effect on mushroom production

Spawn-run compost was routinely analysed for the presence of moulds. In a bulk spawn-running system, abundance of moulds was associated with low average yields and high levers of 25nm virus. Conversely when less moulds were present yields were higher and virus levels lower. We suggest that the presence of moulds in bulk spawn-run compost, other than Agaricus and S. thermophilum, indicate that hygiene practices are not 100% effective. Routine monitoring of mould levers may therefore highlight unnoticed breeches in hygiene. Inoculation of compost at spawning with Acremonium murorum, Penicillium sp., Pythium oligandrum, Trichoderma atroviride and T. pseudokoningii reduced first flush yields by 8 to 94%. Yields recovered to varying degrees in all cases except for Penicillium sp. This work highlights the potential for significant crop losses associated with covert moulds.