New U of I Extension tool helps farmers protect crops, cut costs

MOSCOW, Idaho — A new online tool from University of Idaho Extension is helping farmers across the state better protect crops, reduce unnecessary pesticide applications and save money by tracking how seasonal heat affects crop growth and pest development.

The Growing Degree Day Calculator, developed by UI Extension educator Jemila Chellappa, Canyon County, uses daily temperature data to predict when key crops and insect pests reach critical growth stages. The calculator gives farmers science-based guidance on the best times to apply pesticides, irrigate or fertilize.

“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.”

A growing degree day is a measurement of how hot it’s been over a 24-hour period, comparing the mean temperature against a base value. The calculator is available on the Pacific Northwest Pest Alert Network website at pnwpestalert.net/gdd, operated by UI Extension, Idaho Master Gardeners, Oregon State University and the U.S. Department of Agriculture’s National Institute of Food and Agriculture. The calculator draws localized data from the U.S. Bureau of Reclamation’s AgriMet weather stations. Several Treasure Valley farmers are already using the beta version of the calculator.

Chellappa is working to incorporate the state’s major crops into the calculator and has already added potatoes, sugarbeets, alfalfa, barley and wheat. The software uses site-specific calculations to pinpoint the growth stages of key pests and diseases affecting those commodities.  

By enabling farmers to eliminate unnecessary chemical applications, this calculator also protects beneficial insects or biocontrol agents that predate on pests.  

Furthermore, farmers can use the calculator to track whether their crops are progressing on schedule and to identify likely causes if crop development falls behind where the calculator indicates it should be.

Chellappa is seeking funding and partners to continue expanding the calculator’s capabilities.

Media contacts: 
John O’Connell 
Assistant director of communications 
College of Agricultural and Life Sciences 
joconnell@uidaho.edu 

Jemila Chellappa 
Area Extension educator, cropping systems 
605-690-7699 
jemila@uidaho.edu