Powdery mildew refers to a group of fungal diseases affecting a wide range of plants, characterized by white to grayish powdery spots on the foliage and sometimes stems, flowers, and fruit. Each species of this fungus targets specific plant hosts, making it a common issue in both gardens and agriculture. The disease thrives in warm, dry climates with cool nights, and can spread rapidly in crowded plant conditions where air circulation is poor.

The lifecycle of powdery mildew includes both sexual and asexual phases, allowing it to survive in various conditions and overwinter in plant debris or on perennial plants. Initial infections are often unnoticed until the characteristic powdery growth appears on plant surfaces. If left unchecked, it can lead to leaf yellowing, curling, and eventually plant weakness or death, particularly in severe cases or with highly susceptible plant varieties.

Popular Plants Affected by Powdery Mildew:
Roses
Grapes
Squashes and cucumbers (Cucurbits)
Ornamentals like lilacs and phlox
Many types of fruit trees, vegetables, and ornamental plants