Hollyhock Rust: Identification and Control for Lace-Like Leaves

Those yellow dots on leaf undersides progressing to lace-like foliage indicate hollyhock rust—a fungal disease producing orange-yellow pustules underneath leaves. Thousands of spores spread via splashing water and wind, infecting nearby plants. The fungus overwinters in plant debris.

Spray now with a fungicide containing chlorothalonil, mancozeb, sulfur, neem oil, or myclobutanil. In fall, cut all stalks to ground level, collect all leaves, and destroy them to break the disease cycle. Good sanitation is essential for long-term control.