Used oyster mushroom substrate (Pleurotus ostreatus) helped protect banana plants from root-damaging nematodes (Radopholus similis). In two greenhouse trials, the spent substrate reduced nematode populations, improved soil nutrients like nitrogen and potassium, and boosted overall plant health, leading to better root and shoot growth with less root rot. Researchers believe the beneficial effects come from leftover mycelium and natural fungal compounds that suppress or disrupt the pests.