Each week we will be offering the air Growing Degree Days (GDDs) for corn that have accumulated to date from 13 locations across the team 8 county area.  A thank you to our intern Peter Burritt for pulling this information together.

Four planting dates will be listed and included will be:
GDDs Season To Date
15 Year Average GDDs
30 Year "Normal" GDD
Period of Record - Max and min recorded GDDs for that time period

See: Growing Degree Day Calculator

Growing Degree Days for corn are Base 86/50 degree F and calculated by taking the average daily temperature, ((Daily Max Temp - Daily Min Temp)/2) - 50.  But the maximum temperature cannot be more than  86 degree F and the minimum less than 50 degree F.

Planting date GDDs continue above the 15 year average and definitely above the 30 year "normal" for the date and the May 10 and 20 planting dates are near record GDDs for this date.

Tasseling/silking (1200 GDDs) should be completed at most locations except for corn planted June 1 and at higher elevations.  If you know your GDDs for your hybrid to physiological maturity(black layer) subtract off 150 GDDs to get you roughly the GDDs needed to silage harvest dry matter for that hybrid.  Record Silking/Tasseling Dates for Corn Fields

If you saw tasseling/silking in the middle of July look to start harvesting corn silage the last week of August or first week of September.  That may still seem rough in terms of when to begin, but for planning purposes you should be making plans for an early start for corn silage harvest this year unless weather changes drastically to temps below the 15 year average.  It is always hard to think of corn silage being too dry, especially after 2019, but think back to 2018 where dry matters actually started to get ahead of us at harvest which also began late August to early September.

Some of the greatest corn yield losses can occur from drought stress at tasseling/silking.  Kernels 10-14 days after silking (R2-blister stage) may abort from drought stress.  As of 4 August, all eight of our counties were listed in the abnormally dry category at the United States Drought Monitor site and much of Saratoga County indicated as moderate drought: NY State Drought Monitor Map

See the attached table for more of the August 7, 2020 results.
See the attached pdf for a good guide on corn development and our reference for growth stages.