Hollyhock Rust on High Mallow: Identification and Management

Diagnosing the Problem

Your high mallow (Malva sylvestris, or French hollyhock) shows yellowing leaves with spots—classic hollyhock rust (Puccinia malvacearum). The pustules (bumps) are typical of rust fungi.

Control Strategies

The fungus overwinters on lower leaves and old stems. Cut plants back after flowering, clean up debris, and remove infected leaves promptly. For prevention, start fungicide treatments in early spring as leaves expand. Effective options include chlorothalonil (Daconil), neem oil, or myclobutanil (Immunox).