BOISE, ID – A new tool developed in Idaho will help farmers understand when is the best time to apply pesticides.

Jemila Chellappa, an educator at the University of Idaho Extension, created the Growing Degree Day Calculator, which tracks daily temperatures and predicts when pests will reach the stage in their development where they’re hazardous to crops.

Chellappa has developed the tool for pests of potatoes, sugar beets, alfalfa, barley and wheat. She said it’s beneficial for farmers to know the most optimal time to spray pesticides.

“Instead of going in for chemicals without the knowledge of them affecting the beneficial insects and the natural predators already available,” said Chellappa, “this could be both environmental and economically good for growers.”

A growing degree is a measurement of heat over a 24-hour period in a particular area, which tells researchers when a pest will develop based on how much warmth they’ve received. The tool is available on the Pacific Northwest Pest Alert Network’s website.

Chellappa said farmers already are using the tool and her goal now is to incorporate calculations for more pests.

“Include the pest degree-day models for each pest connected to each crop,” said Chellappa, “and also do some manual research on every other key crop of Idaho and include more data on it to deliver growing degree day-based pest alerts.”

Chellappa said she is looking for more collaborations and funding to further expand the Growing Degree Day Calculator.