downy mildew

[ dou-nee mil-doo, -dyoo ]

noun

1. Also called false mildew. any fungus of the family Peronosporaceae, causing many plant diseases and producing a white, downy mass of conidiophores, usually on the under surface of the leaves of the host plant.
2. Plant Pathology. a disease of plants, characterized by mildewed, distorted, and yellowed foliage, caused by any of several fungi of the family Peronosporaceae, as of the genera Peronospora and Phytophthora.

downy mildew

noun

1. a serious plant disease, characterized by yellowish patches on the undersurface of the leaves, caused by the parasitic fungi of the family Peronosporaceae, such as Peronospora destructor: affects onions, cauliflower, lettuce, etc
2. any of the fungi causing this disease

downy mildew

/ dou′nē /

1. A disease of plants caused by oomycete organisms of the order Peronosporales and characterized by gray, velvety patches of spores on the lower surfaces of leaves. Downy mildew of the grapevine nearly destroyed the French wine industry in the 1870s, spurring the development of the first chemical pesticides used on plants.

Word History and Origins

Origin of downy mildew¹

First recorded in 1885–90

Example Sentences

Disease-resistance abbreviations like A and DM indicate that a plant is resistant to anthracnose and downy mildew respectively, crucial information if your garden has had issues with these.

From Seattle Times

"Our hypothesis is that these bladder cells also protect against other plant diseases like downy mildew, a fungal disease which severely limits quinoa yields," says Max Moog.

From Science Daily

The Italian government last month allocated a modest one million euros to help grape producers hurt by downy mildew.

From Reuters

For example, some organic lettuce seeds have an inherent tolerance to downy mildew and resistance to lettuce aphids.

From Salon

For example, the cultivars “Merlot” and “Two Star” are both loose-leaf lettuces, with “Merlot” having deep red, mildly frilly leaves and downy mildew resistance.

From Seattle Times