Early Corn Should be Starting to Tassel

Jarrod O. Miller, Extension Agronomist, jarrod@udel.edu; Cory Whaley, Sussex Co. Extension Ag Agent, whaley@udel.edu; Jake Jones, Extension Agriculture Agent, Kent County, jgjones@udel.edu, Dan Severson, Agriculture Agent, New Castle County, severson@udel.edu

With this heat, we are currently accumulating 30 growing degree days (GDD) per day, so about 100 every three days. Based on the last few years data, the tasseling (VT) stage has started between 1231-1322 GDD. That means fields planted mid-April (Table 1) should start to tassel over the next few days, depending on how planting depth and soil temperature affected early growth in your field. In fact, most fields planted from mid-late April should be at similar stages, with fields planted in early May only about a week behind (if we keep getting 30 GDD per day).

At this stage we begin to pollinate the ear, so stress can play a big role in whether kernels develop or are aborted. With the heat units we are experiencing, our fields will certainly be stressed, so make sure to check your fields for soil moisture and limit what stress you can through irrigation. Any fields pollinating this weekend may get some respite with lower temperatures before they climb back up next week. Scout your fields based on planting date, because even with great management up to this point, yield loss could be out of your hands. A few days difference in growth stage is more important than you may think, as temperatures in July can vary from 80-95 °F easily over a short period. If you are trying to test new products or field management, knowing whether it was heat that took out your field will be important.

Table 1. Accumulated Growing Degree Days Based on Planting Date