Growing Degree Day Model for the Early Growth and Development of Cereals
This heat driven early growth and development model for cereal crops is found in Early Growth and Development of Cereals (Karow, et al., 1993 ). Created jointly by Oregon State University and USDA Agricultural Research Service (ARS) scientists, it is based on cumulative growing degree days from the time of seeding.  An initial seeding depth of 2 inches was used for model prediction and the output will update automatically based on the current number of growing degree days.  This is a simple model and actual development can be affected by differences in variety, climate extremes, disease stressors and other factors.  However, under normal circumstances this model is considered fairly accurate.  The model is predictive through development of the sixth leaf, and should not be considered a substitute for checking field conditions.
PDF - Karow, et al., 1993        
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Autoupdate: 5/22/2015        
Growing Degree Days are in farenheit using base 32 which is suitable for winter wheat.
Seeding Current Crop Year 30 Year (81-10') % of normal Plant Stage Plant Stage
Date GDD  Average GDD GDD Current Predicted 30 year Normal
09/01 4199 3639 115 Beyond 6th Leaf Beyond 6th Leaf
09/15 3784 3168 119 Beyond 6th Leaf Beyond 6th Leaf
10/01 3282 2749 119 Beyond 6th Leaf Beyond 6th Leaf
10/15 2890 2459 118 Beyond 6th Leaf Beyond 6th Leaf
11/01 2508 2202 114 Beyond 6th Leaf Beyond 6th Leaf
11/15 2348 2044 115 Beyond 6th Leaf Beyond 6th Leaf
12/01 2215 1919 115 Beyond 6th Leaf Beyond 6th Leaf