noun. compact usually dark-colored mass of hardened mycelium constituting a vegetative food-storage body in various true fungi; detaches when mature and can give rise to new growth.
noun. form genus of sterile imperfect fungi; many form sclerotia; some cause sclerotium disease in plants.
1. Noun, singular or mass White mold (Sclerotinia sclerotium) appears first as a water soaked spot on a leaf or stem, quickly followed by a white, cottony growth that can kill a plant in four to 10 days.