Growing Degree Days (GDD) and Rainfall through May 14th

Jarrod O. Miller, Extension Agronomist,

Since the rainfall this weekend, cooler temperatures have slowed the accumulation of growing degree days. Since April 14th we had observed a steady trend in GDD accumulation, keeping emergence on track between 7-10 days. Any planting done since May 6th may see delayed emergence, compared to previously planted fields. For those fields planted mid-April you may be at V4-V5. As temperatures warm back up, be prepared to sidedress between V6-V8.

The cooling trend is more apparent when you look at statewide temperatures and rainfall. Compared to nighttime lows, daytime temperatures had a significant drop since the weekend. Rainfall accumulation was between 1.5-2 inches, with the Harrington area still leading the state with 8 inches since April 14th. However, compared to last year these intermittent rainfalls are allowing fields to drain and not leaving all the duck ponds we had in 2018.

Figure 1. Growing degree days in the Dover area since April 14th.

Figure 2. Statewide temperatures since April 14th.

Figure 3. Statewide rainfall accumulation since April 14th.