Controlling Apple Powdery Mildew: Cultural and Chemical Strategies

Apple powdery mildew thrives in humid, shaded conditions. Management combines resistant varieties, cultural practices, and timely fungicide sprays.

Resistant Varieties

Avoid highly susceptible cultivars: Jonathan, Granny Smith, Mutsu (Crispin), Rome, Cortland, Baldwin, Monroe, Idared. Choose resistant types when planting new trees.

Cultural Controls

• Plant in full sun with good air drainage.
• Prune for open canopy to reduce humidity.
• Remove infected shoots in dormant season.

Fungicide Program

If history of severe mildew, spray at 2-week intervals from green tip (bud break) until small green fruit appear. Effective products:

• Sulfur
• Horticultural oils
• Neem oil
• Potassium bicarbonate
• AQ10, Serenade (biologicals)

Best control: first spray at pink bud stage, then every 10–14 days until terminal growth stops.