Growing Degree Days Through June 26

Jarrod O. Miller, Extension Agronomist,

Corn planted on April 24th in Georgetown has just hit the V15 stage, and we have observed the tassel folded up in the 17th leaf ready to emerge. Corn planted before April 24th should be at tassel and pollinating (Table 1), which may suffer during the heat wave this week. Track your fields by each week and watch the temperatures, then check those fields later for aborted kernels. Any corn planted after June 1st is either ready to sidedress or will be next week.

We are in a stronger warming trend with temperatures above the ideal corn growth range (Figure 1). Temperatures above 72°F at night are particularly troublesome during pollination. For the first time this season we have also seen a week with minimal to low rainfall across the state (Figure 2), which will exacerbate stress on corn during this time, so make sure you keep the irrigation going to protect your yield potential.

Table 1: Accumulated growing degree-days based on planting dates through June 18th.

If you planted

Sussex Kent New Castle
14-Apr 1306 1260 1197
21-Apr 1215 1168 1110
28-Apr 1134 1093 1030
5-May 1034 1012 959
12-May 933 914 868
19-May 863 849 808
26-May 723 713 674

V6 = 475 GDD, V12 = 870 GDD, VT = 1135 GDD, R1 = 1400 GDD

Figure 1: Statewide temperatures since April 1st.

 Figure 2: Statewide rainfall accumulation since April 1st.