Production Blog

JEFFERSON CITY, Mo. (DTN) -- Farmers know to get the biggest bang for their fungicide buck, timing is everything. A new online resource from the Crop Protection Network (CPN) can help guide timely application decisions and manage foliar diseases in both corn and soybeans.

The Crop Risk Tool is a free web-based platform that forecasts the risk of key foliar diseases by feeding local weather data into validated risk models. The tool currently has models for white mold and frogeye leaf spot in soybeans and tar spot and gray leaf spot in corn.

"This tool is replacing previous smartphone apps, including Sporecaster and Tarspotter," said Damon Smith, University of Wisconsin Extension field crops pathologist who was involved with the tool's development. "So, instead of standalone apps for one disease, everything is now in one spot. Farmers can break it out by a particular crop and see all the diseases for that crop at the same time, which can help make those fungicide decisions a little easier."

Users can select specific locations to monitor, either by uploading a file containing latitude and longitude coordinates or by navigating to the location on the tool's map and dropping a pin. A user then selects a timeframe, setting the start date to the approximate date of crop emergence for that location.

Risk levels are updated daily based on recent weather conditions, and the tool provides a 7-day forecast to assist in fungicide application planning. The models do assume the disease is present at the selected location and the crop is in a growth stage vulnerable to the disease. Corn is most vulnerable to tar spot and gray leaf spot from the V10 to R3 growth stages. Soybeans are most vulnerable to white mold from the R1 to R3 growth stages and to frogeye leaf spot from R1 to R5.

"I like to look at the 7-day trend of what has happened and then look at the 7-day forecast of what's likely to happen," Smith said. "I find those two trends more informative than just looking at today's instantaneous risk. Say there's moderate risk of white mold, but the risk is trending down, I might hold off a little longer and see if I can either push that fungicide application on my soybeans just a little bit later in that window or -- if the conditions aren't going to be conducive for mold -- maybe I can save that application altogether."

For a foliar disease to occur, three factors must be present simultaneously: a susceptible host plant, a virulent pathogen and a suitable environment. Smith advised getting boots on the ground and scouting fields for disease is still a necessary step.

"These models are risk-based tools using weather data to determine if conditions are favorable for disease to develop," he said. "The risk might be low, moderate or high, but that doesn't mean you have disease in the field. You still need to go out and get your eyes on the crop."

In addition to corn and soybeans, the tool currently has risk models for vegetable crops including potatoes, tomatoes, carrots, beets and onions. Smith said models for other foliar diseases in corn and soybeans are being developed and will eventually be added. These future risk models would help inform decisions for farmers dealing with diseases including northern corn leaf blight, southern rust, Curvularia leaf spot and Cercospora leaf blight.

"So, quite a few more models we're looking to load," he said. "Over the next few seasons, we're also trying to build more functionality in. I'd love to see phenological growth stage models worked in where you could enter your soybean maturity group and planting date, for instance, and the tool would tell you not only if you were at risk for frogeye or white mold, and if you were, it would recommend a product that would give you the highest return on investment."

The application uses data from the IBM Environmental Intelligence Suite gridded site-specific weather data source. Crop disease models were developed based on disease information from university researchers around the country, including CPN partners. The project is powered by the National Predictive Modeling Tool Initiative, a part of the USDA Agricultural Research Service. Each crop disease forecasting tool is sponsored in part by the National Corn Growers Association, United Soybean Board and the North Central Soybean Research Program.

To access the Crop Risk Tool, go here: https://cropprotectionnetwork.org/… .

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Jason Jenkins can be reached at jason.jenkins@dtn.com

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