downy mildew
noun
mass noun
1- mildew on a plant which is marked by a whitish down composed of spore-forming hyphae, penetrating more deeply into the plant than powdery mildew霜霉科真菌; 霜霉病。
1.1
- Family Peronosporaceae, subdivision Mastigomycotina.霜霉科, 鞭毛菌亚门。