The Crop Protection Network (CPN) has launched an exciting new free resource, the Crop Risk Tool, designed to give farmers the power to better understand the best time to manage foliar diseases in corn and soybeans. This tool is the culmination of many years of pathologists walking fields collecting disease data to provide field-specific risk values to guide timely and informed fungicide decisions.
The Crop Risk Tool is a web-based platform that forecasts the risk of key foliar diseases by feeding local weather data into the validated models. Currently, this tool has risk models for tar spot and gray leaf spot in corn, and white mold and frogeye leaf spot in soybeans. The risk models for corn were partially developed through the National Predictive Modeling Tool Initiative. Additional models specific for other cropping systems such as dry beans, potatoes, tomatoes, beets, carrots, and onions are also available.
Users can select fields they would like to monitor and dates they are interested in (upper left of screen, see Figure 1). Risk models are shown on the right side of the screen.
Figure 1. The Crop Risk Tool in action looking at risk level of tar spot and gray leaf spot at multiple Iowa State University Research and Demonstration Farms during the 2024 growing season.
Key Features and Benefits
- Risk levels are updated daily based on recent weather conditions.
- The tool provides a 7-day forecast to assist in planning ahead of incoming weather events.
- This tool covers multiple major above-ground diseases affecting corn and soybeans, making it a versatile resource for integrated disease management.
- Accessible through the Crop Protection Network website, this tool is designed for easy use, with clear instructions for entering field data and interpreting results.
Factors to be aware of when using the tool
- These models assume that the pathogens are present within your field. Remember too, that for any disease to develop, we need a susceptible crop variety, the correct environmental conditions, and the pathogen to be present. Regular scouting is important for understanding if the pathogens are present or have been present in the past.
- Risk prediction tools should only be used during periods when disease development may lead to reduced yields and a fungicide decision may be needed. For example, tar spot and gray leaf spot may lead to yield loss if they occur between V10 (10 emerged leaves) and R3 (milk). Consequently, a fungicide application may be needed to mitigate disease during these growth stages and thereby protect yield.
The Crop Risk Tool is freely available through the Crop Protection Network’s website at https://cropprotectionnetwork.org/crop-disease-forecasting. The platform is supported by research from land-grant universities, their Extension specialists, and the Crop Protection Network. Additional resources, such as fungicide efficacy tables and disease identification guides, are also available on the CPN website to complement the tool’s use.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on May 30, 2025. The information contained within may not be the most current and accurate depending on when it is accessed.
- Professor of Plant Pathology and Microbiology
- Extension Field Crops Pathologist