plasmopara

from The Century Dictionary.

• noun A genus of parasitic fungi of the family Peronosporaceæ, having the mycelium intercellular, the haustoria small and globular, the conidia sometimes forming, swarm-spores, and the oöspores globose, smooth, and brownish. About 15 species are known. P. viticola causes a serious disease of the grape known as downy mildew. See grape-mildew and cucumber mildew.