Powdery Mildews

A variety of fungal diseases effecting ornamental plants and shrubs. While the disease is almost exclusively an aesthetic threat, it can influence taste of fruits and vegetables, as well as overall health of plants. Infection is increased during sunny days and cool nights.

Latin Name

Blumeria graminis

Trees Affected

Ornamentals including Beebalm, Lilacs, Zinnias, Roses, Garden Phlox, various vegetables

Threat to Trees

Minimal to Moderate


Fungal spores travel in wind and overwinter on plants and in plant debris, requiring no water to grow

Signs & Symptoms

Gray, talcum-powder colored coating that covers leaves, flowers, and sometimes fruit of vegetables, perennials and shrubs

Domestic Origins


Geographic Location

North America

Photo Credits