Alcea sp. (Hollyhock) is often attacked by a rust disease. On hollyhock, the rust pustules are pin head in size and may vary from yellow/red to red to brown or gray. Severely infected leaves will die. Fungicides and sanitation may help reduce infection. Leaf spot caused by Cerco sporella causes angular gray to black spots (older spots may have tan centers with brown margins). The spots may merge and tear leaving leaves with a shredded appearance. Fungicides and sanitation helpful.
Written by James Schuster, Extension Educator, Horticulture, and reviewed by Bruce Paulsrud, Extension Specialist, Pesticide Applicator Training and Plant Pathology, University of Illinois at Urbana-Champaign.