WSU Extension

Hortsense

Hollyhock
 
Disease
Rust 



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Caption: Hollyhock rust
Photo by: R.S. Byther
  
Hollyhock : Rust
(revision date: 1/22/2016)


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


Non-Chemical Management
  • 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.
Select non-chemical management options as your first choice!

Chemical Management

Fungicide applications should only be used in conjunction with cultural management options.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Infuse Systemic Disease Control Lawn & Landscape
    Active ingredient: thiophanate methyl  |  EPA reg no: 53883-183-4
  • Hi-Yield Snake Eyes Dusting Wettable Sulfur
    Active ingredient: sulfur  |  EPA reg no: 7401-188-34911
  • Lilly Miller Sulfur Dust Fungicide/Insecticide Dust or Spray
    Active ingredient: sulfur  |  EPA reg no: 802-16
  • Spectracide IMMUNOX Multi-Purpose Fungicide Spray Conc
    Active ingredient: myclobutanil  |  EPA reg no: 9688-123-8845
  • This list may not include all products registered for this use.
Images

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Caption: Hollyhock rust
Photo by: R.S. Byther
Caption: Hollyhock rust
Photo by: R.S. Byther