WSU Extension


Root, stalk, and ear rots 
Seed rot and seedling blight (damping-off) 
Brown marmorated stink bug 
Corn aphids 
Corn earworm 
Cutworms and armyworms 
Spider mites 
Western spotted cucumber beetle 

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Caption: Corn aphids
Photo by: Unknown
Corn : Corn aphids
(revision date: 1/22/2016)

Aphids are small, soft-bodied, pear-shaped insects. They may vary in color from yellow to green to dark. Aphids typically feed in colonies on the leaves, often preferring the newer growth. Infested leaves turn yellow and may wilt or show other signs of water stress. Feeding aphids often produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a dark growth of sooty mold.
Management Options

Non-Chemical Management
  • Encourage natural enemies including ladybird beetles, lacewings, syrphid (hover) fly larvae, and parasitic wasps. Avoid use of broad-spectrum insecticides which kill beneficial insects.
  • Hand-wipe to control small, localized infestations when practical.
  • Wash aphids from plants with a strong stream of water.
  • Control honeydew-feeding ants, which may protect aphid colonies from predators.
  • Provide proper nutrition. High levels of nitrogen in the foliage encourage aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer when practical.
Select non-chemical management options as your first choice!

Chemical Management

Thorough coverage of the foliage is important, including lower leaf surfaces. Apply in early morning or during the evening when bees are not present. Do not apply unless leaves are dry. Read the product label for timing between last application and harvest.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Safer Brand Insect Killing Soap with Seaweed Extract II [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 42697-59
  • Whitney Farms Insecticidal Soap for Organic Gardening [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 67702-21-73327
  • This list may not include all products registered for this use.

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Caption: Corn aphids
Photo by: Unknown
Caption: Aphid cast skins
Photo by: R.S. Byther