Powdery Mildew on Holly: Fungicide Options and Application Timing

Symptoms

White powdery coating on holly leaves causing defoliation is powdery mildew. It appears as gray-white patches on leaf surfaces, often with leaf curling before the fungus is visible.

Fungicide Program

Spray at first detection. Repeat on a regular schedule (more often in cool, damp weather). Use a spreader-sticker. Cover both leaf surfaces. Effective fungicides: triadimefon (Bayleton/Strike), triforine (Funginex), thiophanate-methyl (Cleary's 3336), propiconazole (Banner). Check local nursery for availability.