Powdery Mildew Control: Identification, Resistant Varieties, and Treatments

Powdery mildew is a common summer disease starting with cool nights and warm, humid days—symptoms persist even as days warm.

It's a "parasitic" fungus resting on leaf surfaces, absorbing sap from plant cells, causing twisted, gnarled leaves. Common hosts: euonymus, rose, phlox, lilac, crape myrtle. Powdery mildews are host-specific—rose mildew doesn't attack lilac; dogwood mildew doesn't attack phlox. Over 1,600 fungal species cause it.

Crape myrtle blooms become sparse as disease aborts buds. Wise alternative: ONLY plant crape myrtles with Native American names ('Natchez', 'Muscogee', 'Tuscarora')—specifically selected for mildew resistance.

Severe winter pruning of crape myrtle increases powdery mildew likelihood the following summer.

For euonymus, so terribly susceptible, replacing the shrub with a less problematic plant is recommended.

Chemical Controls (available at local garden centers):

• Mancozeb
• Bonide Infuse
• Chlorothalonil
• Propiconazole
• Myclobutanil

Organic Controls: Remedy, wettable sulfur, horticultural oil (including neem oil).

powdery mildew on dogwood leaves

powdery mildew on crape myrtle

powdery mildew on rose

powdery mildew on euonymus