Treating White Mold on Rose Stems in Humid Maui Climate

Powdery Mildew Management for Hawaiian Rose Gardens

A Maui gardener needs to identify and treat white mold on rose stems in humid conditions.

Diagnosis: Powdery Mildew

White mold on stems in humidity is powdery mildew. Red and orange roses are most susceptible, but all colors can be affected.

Treatment Options

Organic: 1 tablespoon baking soda per quart water, spray daily until resolved.

Chemical: Any rose fungicide works. Funginex is highly effective but may be restricted under pesticide regulations.

Prevention and Monitoring

• Identify most susceptible varieties—they'll show symptoms first when conditions favor mildew
• Improve air circulation through pruning and spacing
• Monitor closely during humid periods