downy mildew


: 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
: a plant disease caused by a downy mildew

Example Sentences

Recent Examples on the Web Basil is one of the few herbs that sometimes struggles with diseases such as downy mildew and leaf spot, so look for newer varieties, such as columnar basil, which is more disease-resistant. Arricca Elin Sansone, Country Living, 17 Mar. 2023 Agastache is apparently prone to downy mildew. oregonlive, 8 Oct. 2022 Spray dormant fruit trees now to prevent leaf curl, fire blight, downy mildew, aphids, scale and other problems in spring and summer. Nan Sterman, San Diego Union-Tribune, 7 Jan. 2023 Perhaps the most common problem is downy mildew that causes yellow areas to form in the leaves that turn brown. Tom Maccubbin, Orlando Sentinel, 24 Sep. 2022 Products labeled for downy mildew and other leaf spots include copper fungicides, Dithane M-45 and Daconil. Tom Maccubbin, Orlando Sentinel, 24 Sep. 2022 Fungicides can be used when the first spots of downy mildew are noted. Tom Maccubbin, Orlando Sentinel, 3 Sep. 2022 Botrytis spores can start on the blooms, and black spot and downy mildew spores can start on the leaves and move on to invade the canes. Nan Sterman, San Diego Union-Tribune, 7 Aug. 2021 Basil downy mildew flourishes in warm, humid environments. Tim Johnson,, 26 Aug. 2019 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'downy mildew.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1886, in the meaning defined at sense 1

Time Traveler
The first known use of downy mildew was in 1886

Dictionary Entries Near downy mildew

Cite this Entry

“Downy mildew.” Dictionary, Merriam-Webster, Accessed 1 Jun. 2023.

More from Merriam-Webster on downy mildew

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!