For Cherries, the timing of growth stage progressions through the season is dependent on both the variety and environmental cues such as day length, or temperature. The Sour Cherry growing degree day model uses heat units and time as a method to estimate plant phenological stages through the growing season. Researchers have developed a model which can be used to relate the amount of growing degree day unit accumulation to rough percentages of plants at different crop growth stages for the Sour Cherry variety Montmorency. This can be helpful as a crop management tool, or to predict harvest timing.
Calculating Growing Degree Days
For this model, a lower temperature threshold of 4C and an upper threshold of 40C is used to calculate growing degree day accumulation beginning on March 1st, or the start of the growing season or when the crop is at the side green stage. Growing degree days can be calculated from daily high and low temperatures, using a sine model, or via the Pest Prophet app, which uses hourly temperature data for a given field. These growing degree day calculations can be used to give an estimate of crop growth stage, using the table below.
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