MOSCOW, ID –  A new digital tool from University of Idaho Extension is giving farmers across the region a science-based way to save money, cut pesticide use, and track crop health.

The Growing Degree Day Calculator, developed by Canyon County Extension educator Jemila Chellappa, uses daily temperature data to predict when crops and insect pests reach critical growth stages. The tool is designed to help farmers determine the best times to apply pesticides, irrigate, or fertilize, potentially reducing unnecessary costs and chemical applications.

“For generations, farmers have turned to the calendar, but the calendar can’t tell you what the weather has or hasn’t done,” Chellappa said. “We now have a user-friendly, real-time tool to help farmers, researchers and advisors across the Pacific Northwest track crop development and pest stages based on temperature, not just the calendar.”

The calculator, available at pnwpestalert.net/gdd, is part of the Pacific Northwest Pest Alert Network, operated by UI Extension, Idaho Master Gardeners, Oregon State University, and the U.S. Department of Agriculture’s National Institute of Food and Agriculture. It draws localized weather data from the U.S. Bureau of Reclamation’s AgriMet stations. Farmers in the Treasure Valley are already using the beta version.

Chellappa has added major Idaho crops, including potatoes, sugarbeets, alfalfa, barley, and wheat, into the system. The software also accounts for site-specific conditions and identifies growth stages of key pests and diseases. By targeting pesticide use more precisely, the calculator helps protect beneficial insects that naturally prey on pests.

Beyond pest management, the tool allows farmers to assess whether crops are on schedule and to investigate potential reasons if growth falls behind. Chellappa is seeking additional funding and partnerships to expand its capabilities statewide.