Should Iowa farmers apply foliar fungicide to corn?

Wallaces Farmer recently reported a summary of a study conducted by the Iowa Soybean Association On-Farm Network, the ISU Corn and Soybean Initiative, and the ISU Northwest On-Farm research program regarding the use of foliar fungicide on Iowa corn. Below are results and recommendations based on the study’s findings.

Is applying foliar fungicide to Iowa corn worth the cost?

  • For the total 574 observations included in the above study, the overall mean yield response was 4.04.
  • Yield response of small plot trials (173 observations) was 4.39bu/A, compared with 3.89 bu/A for on-farm strip trials (401 observations).
  • Applications at the corn growth stages VT, R1 or R2 resulted in the highest mean yield response (4.12 bu/A, 4.21 bu/A and 4/17 bu/A, respectively).
  • Based on the price of corn of $3.72 and $24 product + application cost, the breakeven yield response is 6.45 bu/A.

Click here for the full list of study results.

Should you apply fungicide this year?

Alison Robertson and Daren Mueller with the Department of Plant Pathology at Iowa State Extension recommend doing some homework before applying foliar fungicide. Consider the price of corn, price of product plus application, and drying costs. Scout fields to determine disease pressure, consider hybrid susceptibility and the disease history of the field. If you see several spots, and you are growing a susceptible hybrid, you may want to consider spraying a fungicide.

Mark Grundmeier, seed product manager with Latham Hi-Tech Seeds says to remember that fungicides are effective only on fungal diseases, including Northern and Southern Leaf Blight, Northern Leaf Spot, Anthracnose Leaf Blight, Gray Leaf Spot, Eyespot, Common and Southern Rust, and Common Smut.

For more information about foliar fungicide, and possible best dates for application, click here.