Pest degree day calculators available for commodity, specialty crop growers

CHAMPAIGN – Two updated pest degree day calculators from the Prairie Research Institute, PRI, are available for commodity and specialty crop growers in Illinois.

The calculators feature seven-day weather forecasts, graphs and insect emergence maps to track accumulated degree days and light for the most notorious pests.

The tools are available online at 

The calculators are free, but registration to the WARM website is required.

Since temperature controls the rate that insects develop, the new degree day calculators use data from the Illinois Climate Network, ICN, so growers can calculate degree days accumulated in their region of the state for specific pests, such as the codling moth, spotted wing drosophila, corn rootworm or emerald ash borer.

“When we see a certain amount of daylight and heat, that factors in to when we start to see insect activity,” said Jennie Atkins, program manager of PRI’s Water and Atmospheric Resources Monitoring Program, WARM. 

“If farmers can track this activity, they can use pest control more efficiently. We wanted to develop tools that would be especially helpful to farmers in planning pest management efforts.”

Atkins and Kelly Estes, coordinator of the Illinois Cooperative Agriculture Pest Survey, surveyed growers around the state to find out how to improve WARM’s previous pest degree day calculator. 

They found that growers want degree day information on specific pests that are currently problematic, they want to be able to plan based on current and future weather data, and they want tools they can use anywhere, especially on cell phones and tablets.

Previous degree day tools used the ICN data to provide current degree day accumulations, and projected degree days were based on historical weather averages. 

The ICN data remain vital for providing pest degree day information on the calculator.

The local seven-day forecast, based on weather forecasts from the National Weather Service, allows growers to know what to expect and to zero in on the potential progression of insect life stages, while also determining when crops will be the most vulnerable.

In striving to develop new tools to aid in the timing of improved pest management, there are now three state maps, one each for the corn flea beetle and the prediction of potential Stewart’s Wilt severity, Japanese beetle emergence and brown marmorated stinkbug activity.

“As the growing season progresses, we want to provide information not only quickly but also in multiple ways, giving growers a heads-up before insect pests start to emerge or reach problematic life stages,” Estes said.

The new tools were funded by the Illinois Department of Agriculture Specialty Crop grant program and the Illinois State Water Survey, a part of PRI. 

The Gazette-Democrat

112 Lafayette St.
Anna, Illinois 62906
Office Number: (618) 833-2158

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