How to Manage Pests

Pests in Gardens and Landscapes

Pest identification and confirmation—Powdery mildew

Powdery mildew and downy mildew may sometimes be confused. Here are some differing characteristics of the two.

Charateristic Downy mildew Powdery mildew
Favorable conditions
Cool, wet
Warm, dry
Location of white spores on leaves
Undersides
Both sides of leaves
Occurence of spores
Only after rain or irrigation
Abundant even in absence of water
Shape of discolored splotches
Bordered by veins; jagged
Circular
Under hand lens
Spores on branched stalks
Spores in chains

Spores of powdery mildew
Spores of powdery mildew

Spores of down mildew
Spores of downy mildew


Statewide IPM Program, Agriculture and Natural Resources, University of California
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