Growing Degree Days Through June 26

Jarrod O. Miller, Extension Agronomist, jarrod@udel.edu

Corn planted on April 24^th in Georgetown has just hit the V15 stage, and we have observed the tassel folded up in the 17^th leaf ready to emerge. Corn planted before April 24^th 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 1^st 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 18^th.

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

Figure 1: Statewide temperatures since April 1^st.

 Figure 2: Statewide rainfall accumulation since April 1^st.