- Plant Pathology. a disease of plants, characterized by a cottony, usually whitish coating on the surface of affected parts, caused by any of various fungi.
- any of these fungi.Compare downy mildew, powdery mildew.
- any of similar coatings or discolorations, caused by fungi, as that which appears on fabrics, paper, leather, etc., when exposed to moisture.
verb (used with or without object)
- to affect or become affected with mildew.
- any of various diseases of plants that affect mainly the leaves and are caused by parasitic fungiSee also downy mildew, powdery mildew
- any fungus causing this kind of disease
- another name for mould 2
- to affect or become affected with mildew
n.mid-13c., mildeu “honeydew, nectar,” from Old English meledeaw “honeydew” (sticky stuff exuded by aphids), from Proto-Germanic compound of *melith “honey” (see Melissa) + *dawwaz “dew” (see dew). Cf. Old Saxon milidou, Dutch meeldauw, German Meltau “mildew.” First element in many cases assimilated to forms of meal (n.2) “ground grain.” As a kind of fungus it is first recorded mid-14c., so called from its being sticky and originally growing in plants. As a verb from 1550s. Related: Mildewed.
- Any of various fungi or oomycete organisms that form a white or grayish coating on surfaces, such as plant leaves, cloth, or leather, especially under damp, warm conditions. Powdery mildews are important plant diseases usually caused by ascomycete fungi, while downy mildews, including a serious disease of grapevines, are caused by oomycetes.