Written by: Jodi Azulai, UC Statewide IPM Program
To accurately time insecticide treatments see our online presentation about using degree-days for pests in fruit and nut trees. While we can’t control heat waves such as the recent one, we can measure daily temperatures to protect our orchards from several important insect pests such as navel orangeworm, San Jose scale, orange tortrix, and codling moth.
Using degree-days to time treatments allows you to reduce insecticide use by targeting the most susceptible insect stage, attaining maximum control and reducing costs. Monitoring and using degree-days allows for the correct application timing of reduced-risk products preserving many of the parasites and predators that control other orchard pests.
Walt Bentley, retired UC IPM Advisor, narrates the 15-minute presentation and explains the basics:
- How heat influences insect development
- What a degree-day is
- How degree-days accumulate
- What data is needed to calculate degree-days
- The benefits of using degree-days to time insecticide treatments
The presentation can be accessed on the UC IPM website at
In the future, look forward to a second degree-day presentation on how to use UC IPM Web site tools and information for calculating degree-days.