Powdery Mildew on New Knockout Rose: Organic Controls

Diagnosis

A newly planted 'Knockout' rose (5 days in ground) shows whitish spots on leaves—classic powdery mildew. Buds disappeared. No insects visible. The rose was a Mother's Day gift.

Organic Management

• Cultural: Minimize watering; allow foliage to dry between waterings. Avoid high-nitrogen fertilizers (stress plants). Use a good organic rose fertilizer.
• Sprays (rotate):
  • 1 cup milk per gallon water
  • 1 tbsp baking soda per gallon water
  • Leftover coffee (acidic)
  • Liquid seaweed
• Water source? Nearby irrigation may increase humidity.

Knockouts are susceptible to mildew. Early organic intervention prevents spread.