Growing Degree Days (GDD) and Rainfall through May 7th

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

Compared to last year, our soils and weather have been more conducive to planting. Our no-till fields at the station have been the best to plant in this year, while rainfall this weekend has slowed some work in fields that received conventional tillage.

If you have been scouting your fields, there should certainly be some corn emergence across the state. It takes up to 120 GDD to see corn emergence, and fields planted by April 28th in Sussex County should all have emergence. Only New Castle County has been cool enough to slow emergence, but any field planted by last Sunday should still see corn pushing through in the next few days.

Table 1: Accumulated growing degree days based on planting dates through September 4th.

If you planted -> Apr 14 Apr 21 Apr 28
Sussex 304 214 132
Kent 285 192 117
New Castle 276 189 109

Emergence = 120 GDD, V6 = 475 GDD.

Similar to 2018, there is a variable amount of rain that has fallen across the state since April 14th. The region around Harrington has received the most, at almost 6 inches in the last few weeks, while Newark and Dover have received about 3.5 inches. In 2018, Georgetown had almost 5 inches at this point, similar to 2019. While the total amount of rainfall across the state between 2018 and 2019 is similar, the major difference is the size of the storms. In 2018 Georgetown observed an event that deposited almost 3 inches, while this year we have received several 1 inch events over several weeks, giving soils enough time to drain and dry out.

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