Master Gardener Class 2011

Carol Fryer

How I Did My ResearchHow I Did My Research

• Google Google search by topic and specify a university or extension website

• Search examples: Search examples: degree days site:edu

growing degree days site:vt.edu degree days site: ext.vt.edu

Results of Google Search

My ChoicesMy Choices

So What are Growing Degree Days?So What are Growing Degree Days?

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!

What does it involve?What does it involve?

* Record daily high and low temperatures and find an average temperature for the day.

Example: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.

Mathematical Equation of GDDMathematical Equation of GDD

Max temperature + Minimum Temp /2 minus Base Temp = Daily GDD

70°(MT) + 50°(min t) /2 = 60°– 50°(BT) = 10 GDD

ChartingCharting

Winfield Solution GDD CalculatorWinfield Solution GDD Calculator

GDD for InsectsGDD for Insects University of NH - Growing Degree Days for Insect Management,

Nancy E. Adams, Extension Educator, Agricultural Resources

Insect GDD - Cornell UniversityInsect GDD - Cornell University

Summary – GDD & Insect Control 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

Don’t Forget the Beneficial Don’t Forget the Beneficial InsectsInsects

ResourcesResources

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

QuestionsQuestions

The END

Potato insect larva - handmade candy