2/15/2019 1 Update on Corn Earworm Management in Sweet Corn Rick Foster Department of Entomology Purdue University Corn Earworms • Primary pest of sweet corn in the Midwest • Overwinter at some level in most of Indiana • Migrate north from southern locations; migration can occur any time depending on weather patterns • First generation (June) is usually fairly small • Second generation (August) is usually very large • Sweet corn harvested in late August and September is usually severely attacked by corn earworms
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Update on Corn Earworm Management in Sweet Corn Rick …...2/15/2019 4 2018 Sweet Corn Insecticide Trial Insecticide Rate/Acre Application Dates Damaged Kernels/Ear % Clean Ears Untreated
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2/15/2019
1
Update on Corn Earworm Management in Sweet Corn
Rick Foster
Department of Entomology
Purdue University
Corn Earworms
• Primary pest of sweet corn in the Midwest
• Overwinter at some level in most of Indiana
• Migrate north from southern locations; migration can occur any time depending on weather patterns
• First generation (June) is usually fairly small
• Second generation (August) is usually very large
• Sweet corn harvested in late August and September is usually severely attacked by corn earworms
2/15/2019
2
Corn Earworm Biology
• Females prefer to lay eggs singly on green silks
• Eggs hatch in about 3 days, depending on temperatures
• When eggs hatch, larvae crawl down silk into the ear tip
• Larvae do little or no feeding until they are inside the tip of the ear
• Adult activity can be measured with pheromone traps
General Management Strategy
• A contact insecticide must be present on the silk between the egg and the tip of the ear prior to egg hatch
• Problem is compounded by the growth of silks (1 inch per day) so that each day there is unprotected silks
• Because of silk growth, multiple applications are required
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What Determines the Level of ControlYou Will Receive?
• Correct insecticide
• Correct timing
• Correct placement
Correct Insecticide2017 Insecticide Trial Results
Insecticide Rate per Acre % Clean Ears Damaged Kernels/Ear