Hollyhock rust

Rusts and smuts

Pathogen

Puccinia malvacearum.

Hosts

Alcea, Althaea, Lavatera and Malva.

Symptoms

Small, brown spots develop on the underside of foliage. Raised, bright yellow or orange pustules are visible on upper leaf surfaces. When disease is severe, large portions of the foliage are killed.

hollyhock rust entire plant
Lesions caused by hollyhock rust on the upper leaf surface.

Spread

Spores can overwinter on diseased plant tissues and infect new foliage the following year. Spores are also produced on susceptible weeds. These can subsequently infect and cause disease on hollyhocks. Spores are wind-dispersed.

hollyhock rust lower leaf surface
Numerous rust pustules on hollyhock foliage.

Management

Disease control on seedlings is especially important. Fungicide applications at regular intervals are necessary when disease is severe. Plants should be cut back as soon as flowering is done. Plant debris should be removed and destroyed, not composted. Several weeds in the mallow family are also susceptible and should be controlled to limit inoculum in the growing area.

hollyhock rust upper leaf surface
Raised, orange-brown pustules of hollyhock rust on the lower leaf surface.

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The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the AgBioResearch, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.