Downy Mildew - Rose Tree Downy Mildew Disease

Janna Beckerman
Department of Botany and Plant Pathology, Purdue University
BP-68-W
Figure 1. The different strains of
downy mildew can be very host
specific, or it can infect many
members of the daisy family, including
this Rudbeckia.
Photo by Janna Beckerman
Figure 2. The large lesions caused by
downy mildew can easily be mistaken
for other kinds of damage.
Photo by Janna Beckerman
downy mildews are a group of closely related
pathogens that can cause major damage in the nursery,
greenhouse, and landscape in the form of leaf spots,
blights, and distortions. Some common downy mildew
hosts include alyssum (Alyssum spp.), aster (Aster spp.),
butterfly bush (Buddleia spp.), coreopsis (Coreopsis
spp.), craneâ€™s bill or hardy geranium (Geranium spp.),
Geum (Geum spp.), kale (Brassica oleracae), dead
nettles (Lamium spp.), pansy (Viola x wittrockiana),
phlox (Phlox spp.), rose (Rosa spp.), rosemary
(Rosemarinus spp.), sage (Salvia spp.), snapdragon
(Antirrhinum), veronica (Veronica spp.), viburnum
(Viburnum spp.), and violets (Viola spp.).
This publication examines downy mildews in the
home landscape and provides strategies for managing
the disease.

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