Green mould contamination of Pleurotus pulmonarius cultivation in Malaysia: Unravelling causal agents and water source as critical factors.

Green mould contamination causes a significant challenge to mushroom growers in Malaysia leading to reduced yields and economic losses in the widely cultivated and marketed edible grey oyster mushroom, Pleurotus pulmanorius. This study aimed to identify the causal agents of green mould contaminants and determine the critical points in the cultivation process in the farm that contribute to green mould contamination. Samples of mushroom substrate (sawdust), spawn substrate (corn), environmental sources and tools were collected at different stages of mushroom cultivation. As results, the causal agents of green mould contamination were identified as Trichoderma pleuroti, T. harzianum and T. ghanese. Prior to steam pasteurisation and after steam pasteurisation, the spawn substrate and mushroom substrate were found to be free of Trichoderma. However, Trichoderma was detected in water, air within the production house and on cleaning tools. This findings suggests that water could serve as the source of green mould introduction in mushroom farms, while cultivation practices such as watering and scratching during the harvesting cycle may contribute to adverse green mould. Understanding these critical points and causal agents provides information to mitigate the green mould contamination throughout the grey oyster mushroom cultivation process.