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Integrated Pest Management · Agriculture and Natural Resources

University of California

Transcript: How to Use UC IPM Online Degree-day Tools

Open the video in a new window.

To calculate degree-days, go to the UC IPM home page found at
Find Quick Links at the bottom of the left column and click on Weather, models & degree-days.
Words Visual
Scroll down to Pest and plant models.  
These pest names link to calculators preset with degree-day model information recommended by the University of California. Indicate pest names, such as Beet armyworm, California red scale, Codling moth
Let's look at Peach twig borer. Choose Peach twig borer
Next we choose a crop. Let's select Almond from the pull-down menu. Pull down menu, choose Almonds
Click on Continue. Click on Continue button

There are three ways to add local temperature data for orchards or fields:

  • Using the UC IPM weather-station database
  • Uploading a file containing temperature data, or
  • Entering temperature data online.
Indicate Weather station from UC IPM database
Indicate Your data file
Indicate Enter data online
For this first exercise, we'll use the weather station database. Choose Weather station from UC IPM database
We'll talk about the other ways later.  
Choose the county where your orchard or field is located. Choose Fresno from menu Select from stations in which California county?
Then set the time period. Accumulation starts on the biofix date. Highlight biofix
For peach twig borer, the biofix is when the first male is trapped in April. Open first pull-down menu, choose April
Open second pull-down menu, choose 4
Open third pull-down menu, choose 2013
For end date I'll enter May 31 since I'm planning a May treatment. Open first pull-down menu, choose May
Open second pull-down menu, choose 31
Open third pull-down menu, choose 2013
Click Continue.  
Choose the weather station closest to your orchard Indicate weather stations in first column
that says, to present Indicate to present in first column for Fresno A. weather station
in the column Period when temperatures are available. Indicate this first column header
Click on the station. We're almost there! Choose Fresno A
The last choice to make is report type: Formatted report or Comma-delimited data file. Indicate formatted report and comma-delimited data file
A formatted report is intended for viewing on your computer or printing. Choose Formatted report button
A comma-delimited data file is for exporting to a spreadsheet program. Indicate Comma-delimited data file button
Click Calculate.  
Here is the formatted report. The large table contains the accumulation Highlight Accumulated column in second table
of degree-days from the biofix date, April 4 through the end date, May 31. Indicate dates in first column of second table
This table shows the time in degree-days for each generation and spray timings. Indicate first table, titled Typical generation periods and spray timing
So for example, if you want to know when to apply an early-generation insecticide application, look in the results table under degree-days, accumulated. Indicate 400-500 under Early generation
Scroll down to see when 400 to 500 degree-days accumulated.
In this example, about 400 degree-days correspond to May 1, 2013. Highight 401.48
About 500 degree-days correspond to May 6, 2013. Highlight 499.84
Therefore, any time from May 1 through May 6 would be the optimal time to apply an insecticide, because most of the peach twig borers in your orchard will be at their most vulnerable stage to the insecticide. Highlight all data between May 1 and May 6
It's easy to use the online degree-day calculator tool! Get to the Pest Management Guidelines by clicking the link here. Move up page, choose Pest Management Guidelines
In the Pest Management Guidelines, you'll find the information on degree-day treatment timing. Indicate Monitoring and Treatment Decisions
And if you're already in the Guidelines, you can find a link to the degree-day calculators. Choose Calculate degree-days
[UPLOAD YOUR DATA FILE] Move back to Peach Twig Borer model page with Specify source of temperature data
Now let's find out how to upload a temperature data file. Choose Your data file
The file must be carefully formatted to work with this program. Read more about formatting requirements here. Indicate text file (comma or tab delimited) format
Select Your data file, then click the Choose file button. [Or the Browse button]
Locate your file and click Choose. [Or the Open button]
If all goes well, your file name shows up here. File name on Web page next to button
Click Continue.  
Choose the output format as before, Choose Formatted report button
and access the results page. Choose Calculate
The third option is to enter your data online. Move back to Peach Twig Borer model page with Specify source of temperature data
To do this, choose Enter data online  
and then Continue.  
Enter the daily minimum and maximum temperatures in Fahrenheit or Celsius. Choose Fahrenheit or Celsius, then type example temperature data into fields under Min and Max columns
Select your format output as before, Choose Formatted report button
and click on Calculate.  
To print a reference degree-day table and hand-compute degree-day accumulations, go back to the weather, models, and degree-days page. Choose Degree-days menu to move back to Weather, models, and degree-days page
Next to peach twig borer we'll click on Table. Scroll down page to reach Peach twig borer
To use this table, locate the daily high at the maximum temperature column, Indicate first column
and the daily low temperature here at the minimum temperature row. Indicate top row
For example, if today's high was 74°F, Highlight 74 in first column
and the low was 56°F, Highlight 56 in top row
fifteen degree-days accumulated for peach twig borer. Scroll down under 56 column, highlight 15
For the dates you're interested in, add the daily accumulation values until you reach the degree-day accumulations indicated for treatment.  
[CUSTOM DEGREE-DAY CALCULATOR] Move back to Weather, models, and degree-days page
The last tool I'll mention is the custom degree-day calculator. Scroll to end of page for Degree-day calculator
It allows you to enter thresholds for any model Indicate Enter lower field, then Enter upper
and specify the method of calculation. Indicate Calculation button