downy mildew

noun

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

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First Known Use of downy mildew

1886

in the meaning defined at sense 1

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