powdery mildew

American  

noun

1. any of various parasitic fungi of the ascomycete order Erysiphales, which produce a powderlike film of mycelium on the surface of host plants.

2. Plant Pathology. a disease caused by powdery mildew, characterized by yellowing and death of the foliage and a white mealy growth of fungus on the surface of above-ground parts.

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powdery mildew British  

noun

1. a plant disease characterized by a superficial white powdery growth on stems and leaves, caused by parasitic ascomycetous fungi of the family Erysiphaceae: affects the rose, aster, apple, vine, oak, etc

2. any of the fungi causing this disease

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powdery mildew Scientific  

/ pou′də-rē /

1. Any of various important plant diseases caused by fungi, especially those of the family Erysiphaceae, which produce powdery conidia on the surface of the hosts leaves and stems.

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Etymology

Origin of powdery mildew

An Americanism dating back to 1885–90

Compare meaning

How does powdery-mildew compare to similar and commonly confused words? Explore the most common comparisons:

• downy mildew vs. powdery mildew

Example Sentences

When tested on wheat, these compounds helped protect against fungal infections such as powdery mildew.

From Science Daily • Oct. 12, 2025

On the other hand, some diseases, such as powdery mildew, thrive in dry, hot environments, which are also becoming more common due to climate change.

From Salon • Mar. 14, 2024

It favors shade and mild temperatures, so if your grapes are not getting full sun, that could increase the likelihood of powdery mildew.

From Seattle Times • Sep. 6, 2023

Maples are prone to many diseases, such as anthracnose, verticillium wilt, and powdery mildew, but I am still confused, so I call Brian Crooks, a forester with the Western Pennsylvania Conservancy.

From New York Times • Nov. 24, 2022

The pole beans in row 8 tend to prevent overspray; this dryness is especially beneficial to humidity-sensitive melons, serendipitously reducing their susceptability to powdery mildew diseases.

From Gardening Without Irrigation: or without much, anyway by Solomon, Steve