In vitro Efficacy of Oyster Spent Mushroom Substrate (SMS) Extract against Major Soil Borne Fungal Plant Pathogens

Spent mushroom substrate (SMS), a by-product of the mushroom industry, is generated in large quantities after multiple cycles of mushroom cultivation. Rich in organic matter, SMS can pose environmental challenges if not properly managed. However, when effectively utilized, it holds potential as a nutrient-rich amendment for crops and may offer protection against various insect pests and plant diseases. This study aimed to evaluate the efficacy of Oyster mushroom SMS against major soil-borne fungal pathogens, Fusarium oxysporum, Rhizoctonia solani, and Sclerotium rolfsii. Both aqueous and methanolic extracts of SMS from three Oyster mushroom species (Pleurotus sapidus, P. ostreatus and P. sajor caju) were tested using agar well diffusion method for their antifungal activity. Among the two types of extracts, aqueous extracts showed superior performance. The aqueous extract of Pleurotus sajor caju SMS demonstrated the highest inhibition against Fusarium oxysporum with 64.66% suppression of mycelial growth, followed by Pleurotus sapidus (58.80%) and Pleurotus ostreatus (57.22%).