We are starting to see corn shooting tassels in a few fields. Although most of the crop was planted later, a few local fields were planted in the first two weeks of March. As a general rule of thumb I usually say it takes 68-70 days for tassel emergence in our earliest planted corn. I went by to look at the Columbia County Grain Corn Trials that were planted on March 14th. A few of the earlier hybrids are showing tassels, while a few others were not. Corn hybrids are also showing differences in their height. I have had a few farmers talk about how fast (or slow) their corn has grown this spring, and we have talked about how until recently the accumulation of GDDs or Growing Degree Days per day was rather low. Corn Growing Degree Days (GDDs) are essentially a measurement of heat accumulation, with the specific base temperature of 50 degrees F, below which little growth occurs. The calculation of GDDs is the average daily temperature minus the base temperature. ((TMax+TMin)/2)-50
I have attached a table showing the GDD accumulation from the FAWN station at Live Oak. This corn field planted on 3/14/14 has accumulated 1241 GDDs since planting according to this weather station. Each hybrid has a different “signature” GDDs to pollination and maturity. For our average full season 117-119 day hybrids it is approximately 1400 GDDs to pollination and 2800 GDDs to maturity. On the recent warm days we are accumulating about 26 GDDs per day.