Fungicide applications can often feel like a gamble. If you don’t spray, you run the risk of incurring a potentially significant impact on your yield from fungal disease. But if you do spray, and the disease was never there, you’ve wasted thousands of dollars that could’ve been invested somewhere else in your operation.
Weather patterns, hybrid susceptibility and field history all factor into the possibility of fungal disease becoming an economic threat. In unpredictable seasons, calendar-based decisions can leave you either underprotected or overspending.¹
The difference between a gamble and a strategic investment is information. Consistent, proactive scouting for early signs of disease in corn and soybean fields helps you identify signs of disease before they escalate. When combined with environmental data, forecasting tools and crop scouting apps, scouting fields can play a pivotal role in making fungicide timing more precise.
Why calendar-based fungicide programs miss the mark
The most recommended timing for fungicide application is VT to R1 in corn and R1 to R6 in soybeans. These windows are based on average disease development patterns and typical environmental conditions.²,³
However, fungicides generally provide protection for 21 to 28 days.⁴ If infection develops outside that window, protection may not align with the peak period when fungal infections become well established. In dry years, disease risk may never justify an application at all.
Calendar-based programs assume average conditions. But fields rarely operate on average.
Building a smarter crop scouting strategy
To make your early-season scouting as effective as possible, consider shifting from traditional calendar-based methods to a customized, data-driven Integrated Pest Management (IPM) approach.⁵
Scouting fields doesn’t have to be complicated, but consistent and thorough scouting makes all the difference. Walk fields regularly, especially in areas with:
- High residue
- Reduced air flow
- History of foliar disease
- Irrigation or prolonged leaf wetness
Also, make sure to look for early lesions in the lower canopy, subtle changes in leaf color or patterns developing in specific zones. And keep records so you aren’t second-guessing where your disease hot spots are next year.
Using data to guide fungicide timing
Alone, regularly scouting fields is powerful. However, when you combine it with weather-based and disease-based forecasting tools, your predictions become more precise.
The Crop Protection Network’s Forecasting Tool provides risk assessments based on real-time weather data. By tracking temperature, humidity and leaf wetness duration, it estimates whether conditions favor disease development in your location. Additionally, The Crop Protection Network provides a library of resource sheets for diseases not yet included in their forecasting tool.
When the risk assessment aligns with what you’re seeing in the field, fungicide applications are more likely to deliver a measurable return on investment.
Instead of spraying based on a growth stage alone, growers can apply fungicides when disease pressure is biologically likely, not just theoretically possible.
Matching products to conditions with crop scouting
Once risk is confirmed through crop and field scouting and environmental data, growers can select the appropriate fungicides, like those within the BASF corn and soybean portfolio, that fit their specific disease spectrum and timing needs. Selecting fungicides with the appropriate modes of action and proven residual performance helps ensure protection aligns with the identified risk window.
You may not be able to predict exactly when fungal diseases will develop, but you can control how you respond. When consistent field scouting is combined with weather-based forecasting tools, fungicide decisions become less reactive and more strategic.
In seasons of sudden variability, better information is often the most valuable input on the farm.
Experts are available to help you make your fungicide decisions. Reach out to your seed retailer, a nearby extension office agent or a seed company professional like your regional BASF representative.
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Endnotes
- Sisson, Adam J., et al. “Use of Scouting Information.” Crop Scouting Basics for Corn and Soybean, Crop Protection Network, 2021, cropprotectionnetwork.org/web-books/crop-scouting-basics-for-corn-and-soybean?section=14-use-of-scouting-information.
- Onofre, Rodrigo Borba. “Scouting for corn diseases.” Youtube, uploaded by Crop Protection Network, May 12, 2023, https://www.youtube.com/watch?v=9g6EOhmByDQ&list=TLGGln-PTerAUhUxNDAyMjAyNg.
- Bissonnette, Kaitlyn. “Scouting for soybean diseases.” Youtube, uploaded by Crop Protection Network, May 12, 2023, https://www.youtube.com/watch?v=r6ZQoCMAnO8&list=TLGGM_NVB9KTQ_4xNDAyMjAyNg.
- Jackson-Ziems, Tamra, and Jenny Brhel. “Corn Disease Update: Fungicide Expectations and Disease Control.” CropWatch, University of Nebraska–Lincoln, 15 Aug. 2024, cropwatch.unl.edu/2024/corn-disease-update-fungicide-expectations-disease-control/.
- Sisson, Adam J., et al. “Chapter 1: Scouting Corn and Soybean as Part of Integrated Pest Management.” Crop Scouting Basics for Corn and Soybean, Crop Protection Network, 2021, https://cropprotectionnetwork.org/web-books/crop-scouting-basics-for-corn-and-soybean?section=chapter-1-scouting-corn-and-soybean-as-part-of-integrated-pest-management
