Growing Degree Days (GDD) and Rainfall Through July 9th

Jarrod O. Miller, Extension Agronomist,

We have witnessed many fields well into R1 (silking) on our earliest maturing varieties planted in April. From here on out, expect steady pollination within your fields in the sequence they were planted. Anything planted by May 20th should be at VT (tassel). Fields that with flooding issues will have corn tasseling at the waist. With less leaf area for photosynthesis, expect lower yields in those regions of the field. Any fields planted early through mid-June still has some time to reach VT.

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

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

Sussex Kent New Castle
22-Apr 1470 1530 1573
29-Apr 1436 1484 1520
6-May 1338 1374 1412
13-May 1240 1268 1308
20-May 1146 1161 1197
27-May 998 1002 1039
3-Jun 848 851 887
10-Jun 734 733 764
17-Jun 605 606 628


Our graph of rainfall across the state is a little off scale, due to the large amount of rainfall received in mid-May. We received a small amount of rain last week, with more in Dagsboro and Delmar than other regions of the state. This graph cannot capture all of the variability statewide, as you can see from the screen capture from DEOS on July 6th. Some hot spots in the state received up to 1.8 inches of rain, while some received none. If you have always thought that storms skipped your farms, you were probably right.

24-hour rainfall for July 6, 2018 from