Maximize Returns on Fungicide Applications

July 24, 2009 07:00 PM

Katie Humphreys, Farm Journal Managing Editor

To get the most out of fungicide applications to corn this summer, you need to know what you're up against to know your return on investment. Daren Bohannan, technical service manager for Bayer CropScience, shared these tips with Corn College attendees to help them make a more informed decision when it comes to fungicide applications.
First, scout fields on a weekly basis. This is the only way to know the level of disease present and when it arrived. Is it gray leaf spot, common rust, northern corn leaf blight or something else? Management recommendations for corn diseases have similarities and differences, so proper identification is critical to achieving the best results.
Just because you see a few lesions on corn plants, doesn't necessarily mean you need to apply a fungicide. Bohannan recommends a fungicide application if 50% of the plants in a field have disease lesions present on the third leaf below the ear or higher prior to tasselling. He also recommends calculating the economics of fungicide applications and assessing risk factors.
Basic economics:
  • Cost of fungicide, cost to apply
  • Price of corn
  • Cost to dry
  • Harvestability
Risk factors:
  • Hybrid susceptibility
  • Environmental conditions
  • Planting date
  • Infection timing
  • Corn-on-corn fields
Don't get antsy and "spray too early to negate benefits,” Bohannan says. "Most fungicides last 14 to 21 days.”
If everything falls in place and depending on the extent of the disease, yield boosts can range from 1 bu. to 11 bu. or more per acre, he adds.

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You can e-mail Katie Humphreys at


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