POWDERY MILDEW Meaning of POWDERY MILDEW in English [powdery mildew] n (1889) 1: an ascomycetous fungus (family Erysiphaceae) producing abundant powdery conidia on the host 2: a plant disease caused by a powdery mildew Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012