Erysiphales is an order of fungi commonly known as powdery mildews, which are obligate plant pathogens affecting a wide range of angiosperms. Members of this order are characterized by their superficial mycelium that grows on the surface of leaves, stems, and flowers, producing a white to grayish powdery coating. They reproduce both sexually, forming cleistothecia (closed fruiting bodies containing asci and ascospores), and asexually, via conidia dispersed by wind. Erysiphales are ecologically significant as agricultural pests, causing reduced photosynthesis, premature leaf drop, and lower crop yields, but they are generally host-specific and often adapted to particular plant species. Their lifecycle and infection strategies make them important subjects of study in plant pathology and disease management.