Definition of downy mildew
1 : any of various parasitic lower fungi (family Peronosporaceae) that produce whitish masses of sporangiophores or conidiophores on the undersurface of the leaves of the host
2 : a plant disease caused by a downy mildew
First Known Use of downy mildew
Learn More about downy mildew
Britannica.com: Encyclopedia article about "downy mildew"
Seen and Heard
What made you want to look up downy mildew? Please tell us where you read or heard it (including the quote, if possible).