Foliar fungicide applications have now become common in corn production, often applied in the absence of disease and in contrast to Integrated Pest Management recommendations. Farmers and County Agents need information to help them understand how fungicides should be used, and when they have optimum efficacy against corn diseases. On-farm research trials were established in Henderson County in conjunction with the County Agent to examine the impact of foliar fungicides in comparison to non-treated controls. Fields were sprayed at late vegetative growth stages with fungicide. Foliar disease severity and yield data were collected, and economic data were used to determine return on investment of foliar fungicide application. In the Henderson County trial location, with final grain price and fungicide application cost, the farmer needed to increase yield by 6.3 bu/A to pay for the cost of the foliar fungicide application.  Yield was increased in the fungicide treatment, but only by 5 bu/A, meaning that the fungicide treatment did not break even, and was not profitable. This research is impactful beacuse it helps farmers learn about the profitability (or lack of profitability) of fungicide applications in their own production system.