WSU Extension

Hortsense

Asparagus
 
Disease
Rust 
Insect
Asparagus aphid 
Asparagus beetle 
Cutworms and armyworms 



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Caption: Asparagus rust asexual fruiting bodies
Photo by: D.A. Johnson
  
Asparagus : Rust
(revision date: 5/7/2015)


Biology
Asparagus rust is a fungal disease affecting the spears and foliage. Early symptoms include the development of oval yellow spots on the spears. These spots contain the fruiting bodies of the fungus, which are the source of infection for new shoots. Later in the summer, symptoms appear on stems and foliage, which develop blister-like pustules. The pustules break open to reveal red-brown masses of powdery spores. In late summer and fall, these spores may appear dark brown to black in color. Onions and related species (Allium sp.) are also attacked. This fungus overwinters on old asparagus stems. Since the fungus develops on spears in the spring, harvesting the spears breaks the life cycle of the fungus. Moisture is required for infection to occur.
Management Options


Non-Chemical Management
  • Remove wild asparagus, wild onions, and related species to reduce sources of infection around plantings.
  • Plant resistant cultivars. 'Jersey Knight', 'Jersey Giant', 'Jersey Centennial', and 'UC-157' have greater resistance than 'California 500' and selections of 'Mary Washington.'
  • Avoid overhead watering and space plantings to reduce humidity.
  • Cut out infected spears and shoots when noticed.
Select non-chemical management options as your first choice!

Chemical Management

Use when harvest is completed. May give only partial control of the summer stage. The effectiveness of oils is unknown in the Pacific Northwest. Oils should not be applied within 2 weeks of any sulfur application or necrotic foliage may result. Do not use oils below 50 degrees F, above 90 degrees F or when plants are under heat or moisture stress. Do not use when foliage is wet as good coverage is essential.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bayer Advanced Natria Neem Oil Conc [Organic]
    Active ingredient: clarified hydrophobic extract of neem oil  |  EPA reg no: 70051-2-72155
  • Monterey Horticultural Oil [Organic]
    Active ingredient: mineral oil/pet distillate light  |  EPA reg no: 48813-1-54705
  • Safer Brand Garden Defense Multi-Purpose Spray Conc [Organic]
    Active ingredient: clarified hydrophobic extract of neem oil  |  EPA reg no: 70051-2-42697
  • This list may not include all products registered for this use.
Images

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Caption: Asparagus rust asexual fruiting bodies
Photo by: D.A. Johnson
Caption: Asparagus rust sexual fruiting bodies
Photo by: D.A. Johnson
Caption: Asparagus rust fruiting bodies
Photo by: D.A. Johnson