Growing Degree Days (GDD) and Rainfall Through July 2nd

Jarrod O. Miller, Extension Agronomist,

Since some have chosen to replant corn fields I have added the first half of June’s GDD. Most corn planted in June should be close or ready to side-dress any additional nitrogen. There should be tasseling across the state in our earliest planted fields, and this is possibly occurring on some very short corn. High temperatures and moisture stress will be an issue during this stage, so add that to your list of possible yield reducing factors this year. Here are the GDD needed to reach these corn stages:

V6: 475 GDD
V12: 870 GDD
VT: 1135 GDD
R1: 1400 GDD

From the rainfall graph you can observe what is very apparent, many dryland fields are in need of rain. Although Georgetown has received 20 inches of rain since April, its moved on down into the profile or into the watershed, and the soil surface is fairly dry. For those who say the east coast is lucky with our annual rainfall accumulations, remind them that timing of that rain is more important.


Table 1: Growing degree days accumulated through July 2nd from the beginning of each week.

  Sussex Kent New Castle
22-Apr 1394 1347 1283
29-Apr 1342 1300 1250
6-May 1234 1190 1150
13-May 1130 1084 1053
20-May 1018 977 959
27-May 861 818 811
3-Jun 708 670 661
10-Jun 586 550 547
17-Jun 449 423 418

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