Problem
How do I treat powdery mildew on my chinese peony 'Karl Rosenfield'?
Paeonia lactiflora 'Karl Rosenfield'
Powdery mildew on a chinese peony 'Karl Rosenfield' usually has one of three causes — watering, light or a pest. Walk through them in order before reaching for a treatment.
Most likely causes
Detailed cause-by-cause guide is being prepared. In the meantime: check watering rhythm, sunlight match, and any visible pests on the underside of leaves.