Missouri DD-50 Rice Model

Gene Stevens, Allen Wrather, Kelly Tindall and Matthew Rhine

Commercial Agriculture Extension Program &
University Outreach and Extension
University of Missouri-Columbia

Welcome to the Missouri Rice Degree Day 50 (DD-50) website. If you are a rice farmer in Southeast Missouri, you will be able to enter information about your field and receive a report with predictions and recommendations based on local weather. This program uses maximum and minimum daily air temperatures to predict when rice growth stages will occur in a field. The program assumes rice growth will not occur with average temperatures below 50oF. The objective of this program is to improve timeliness of rice management decisions by utilizing temperature data from the Commercial Agriculture weather station network. DD-50 reports generated early in the season are based on long term weather averages. As the season progresses new reports can be made with updated rice growth predictions based on weather that has occurred in the season.

To generate a DD-50 report for your rice field, begin by clicking the Start at the bottom of this page. A new screen will appear with blank boxes to enter information.

  1. Field name: Enter the field name in the appropriate box.
  2. Variety and Weather Station: Scroll through the choices of rice varieties and weather stations by clicking on the down arrow in the right corner of each box. Some counties have more than one choice of weather stations. New rice varieties will be added to the list as calibration research is completed.
  3. Emergence date: Enter the number of the month and day that the rice emerged. We define rice emergence as the date that 10 one-leaf rice plants per square foot as present in a field.
  4. Name and Address: If you want to have your name and address appear on each report enter this information in the boxes on the bottom of the screen. This is an optional step. We do not use this information in the model.
  5. SUBMIT Query: Click this button when you have completed the boxes.

The DD-50 report will provide the following information:

  • various weed control options and herbicide cut-off dates
  • when to apply preflood nitrogen and flood the field (beginning tillering)
  • when to check plant area for adequate nitrogen fertility at mid-tillering
  • the recommended nitrogen fertilization rate and timing for the variety
  • when to begin scouting for insects and diseases and control recommendations
  • mid-season -- beginning jointing, time to check plant area, and time to apply mid-season nitrogen
  • time of 50% heading
  • when to stop pumping
  • when to pull the flood and when to harvest.

After you submit a query, a report will appear on your screen. To print the report use the print function of your internet browser. To submit a new field click on the "Back" button in your browser.

A precaution: The accuracy of the growth stage predictions should be verified by the grower at three times during the season. . . (1) beginning tillering, (2) beginning internode elongation, and (3) at 50 % heading. To view illustrations of these growth stages, click on the blue text in your report, where available. Long term temperatures are replaced with actual measurements each day. If the actual daily temperatures are significantly hotter or colder than the long term averages in a given season, the accuracy of predictions should be improved by making new reports.

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