: a superficial usually whitish growth produced especially on organic matter or living plants by fungi (as of the families Erysiphaceae and Peronosporaceae)
: a fungus producing mildew
Conspicuous mass of threadlike hyphae (seemycelium) and fruiting structures produced by various fungi (kingdom Fungi; seefungus). Mildew grows on cloth, fibres, leather goods, and plants, using these substances as food for growth and reproduction. Downy mildew and powdery mildew are plant diseases that affect hundreds of species.