Growing Degree Days

1. Growing Degree Days Master Gardener Class 2011 Carol Fryer

2. How I Did My Research • Google search by topic and specify a university or extension website • Search examples: degree days site:edu growing degree days site:vt.edu degree days site: ext.vt.edu

3. Results of Google Search

5. My Choices

6. So What are Growing Degree Days? Growing Degree Days : • Integrated Pest Management tool • Tracks and predict stages of insect development based on temperature • Uses a mathematical calculation system • Can compare from year to year • Easy and fun to do!

7. What does it involve? * Record daily high and low temperatures and find an average temperature for the day. Example:70º Max & 50° Minimum temp/2 = 60° average daily temperature * Subtract 50º Base Temperature from average temperature: 60 - 50 = 10 Growing Degree Days (GDD) * Add the GDDs for the Accumulated Growing Degree Days(AGDD) and compare to a chart of insect development by degree days.

8. Mathematical Equation of GDD Max temperature + Minimum Temp /2 minus Base Temp = Daily GDD 70°(MT) + 50°(min t) /2 = 60°– 50°(BT) = 10 GDD

9. Charting

10. Winfield Solution GDD Calculator

11. GDD for Insects University of NH - Growing Degree Days for Insect Management, Nancy E. Adams, Extension Educator, Agricultural Resources

12. Insect GDD - Cornell University

14. Summary – GDD & Insect Control • Record daily high and low temperatures and calculate the average temperature • Subtract the base temperature from the daily average • Keep a daily accumulated total of the Growing Degree Days • Check plants for signs of pests • Use list of insect development to predict time periods for potentials pests

15. Don’t Forget the Beneficial Insects

16. Resources Websites: www.extension.unh/agric/GDDays/Docs/growch.pdf www.gardening.cornell.edu www.virginiafruit.ento.vt.edu/Understanding-Degree-Days.html www.wfsag.com/UserFiles/File/GDDCalculator.xls

17. Questions

18. The END Potato insect larva - handmade candy