Each of the many fungi causing downy mildew attack a narrow range of hosts. Spread by wind, rain, and infected seeds, these fungi all require wet conditions, and most must also have cool temperatures (the exception is downy mildew of cucurbits, which can germinate at temperatures as high as 90°F).
Many plants, including, snap-dragons, pansies, roses, marigolds, strawberries, grapes, and most vegetables.Damage:
Leaves show gray, white, or purplish fuzz on their undersides, yellow blotches on the top surfaces.Control:
Keep foliage as dry as possible.