mildew
https://gyazo.com/254105d03f3625152e0b5c3aeb1dd11a
source: By Madan subedi01 - Own work, CC BY-SA 4.0
noun
a thin whitish coating consisting of minute fungal hyphae, growing on plants or damp organic material such as paper or leather.
白かび
verb
affect or be affected with mildew.
ORIGIN
Old English mildēaw‘honeydew’, of Germanic origin. The first element is related to Latin mel and Greek meli ‘honey’.