Twisted, Curled Knock Out Leaves: Powdery Mildew Diagnosis

Jack's second-year Knock Outs had sections of twisted, curled leaves with white spots on unaffected foliage. Jay diagnosed powdery mildew—a fungal disease causing white powdery coating, leaf curling, and distorted growth.

Conditions Favoring Mildew

• Cool, damp days and nights
• High humidity with poor air circulation
• Typically appears in spring/fall; often disappears in summer heat

Treatment

1. Apply Funginex (or similar rose fungicide) per label directions.
2. Improve air flow via pruning.
3. Water at base, not overhead.
4. Clean up fallen leaves.

Note: Powdery mildew rarely kills roses but weakens them. Resistant varieties (many Knock Outs) still get it under ideal conditions for the fungus.