Planning for Corn Diseases

V10 corn adds a new leaf every 2-3 days. At V14, we’re 2 weeks to flowering. It’s the time of year when we can almost see corn growing – increasing the need for focus on disease management programs.

Scouting
Step 1 is scouting. While the disease pyramid is the same for all diseases (host + pathogen + environment), environmental plays a big – and variable – role on an annual basis. Scouting helps determine when a pathogen might be an issue – and when. Looking for guidance? The Crop Protection Network has not only individual disease resources but now includes a disease lookout tool where you can select a disease of concern and see confirmations across the country. It’s no substitute for individual field scouting but can serve as an early ‘warning’.

When a fungicide is needed, product selection is an important part of balancing efficacy and economics. Fungicide selector information on the Crop Protection Network includes two different references of value:

• Fungicide Efficacy for Control of Corn Foliar Diseases includes ratings from trials conducted across the corn growing region of the country.
• Fungicide ROI Calculators allow you to input fungicides costs and disease of interest to predict what type of economic response you can expect.

Stay vigilant. Early Tar Spot finds in 2025 didn’t develop as quickly or as severely as in the past while Southern Rust progressed quickly and with vengeance, resulting in losses after some early fungicide applications had waned in effectiveness. Scouting, disease knowledge, and appropriate fungicide use are all important parts of a sound corn disease management program. These Crop Protection Network tools can be a great help.