Hollyhock: Rust
Photo by: R.S. Byther
Biology
Hollyhock rust is caused by a fungus that overwinters in basal leaves which may live through the winter, or on plant debris. Spores remain viable for at least four months in the soil.
Reddish raised spots develop on leaf undersides and then darken late in the growing season. Stems may also be attacked, and if the case is severe, leaves may dry up and hang down.
Management Options
See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.
Non-chemical Management
Select non-chemical management options as your first choice!
- Pick up and burn all infected plant parts during the growing season, at the end of the growing season, and again in early spring.
- Remove other hosts like cheeseweed (Malva parviflora), Lavatera, Hibiscus, and other Malvaceae plants.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Fungicide applications should only be used in conjunction with cultural management options.
Approved Pesticides
If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.
Additional Image
Photo by: R.S. Byther
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Evidence of noncompliance may be reported through your local Extension office.