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.

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.

As noted previously, Joe Lawrence from the ProDairy Program suggests taking note of tasseling dates as those might serve as a better starting place to project corn silage harvest dates than planting dates. Silage harvest is likely to begin at about 800 GDDs after tasseling for 101-110 day hybrids and 750 GDDs for 96-100 day hybrids.  Using the GDDs after tasseling to harvest and the Climate Smart Farming Website's 15 year GDD data it is possible to make projections as to when corn silage harvest might begin. Record Silking/Tasseling Dates for Corn Fields

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.

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.  You should be making plans for an early start for corn silage harvest this year!  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. Bunker silage should be ~65-70% moisture at harvest, so if you have early planted corn in some of the lower-lying areas (especially in the eastern part of the region this year!), take note of what stage you're at in the coming days: 

We've noticed that fewer fields are being affected by the typical late-season foliar diseases, so the green foliage may mislead you into thinking you still have time - so check your crop to make sure you're on schedule for harvest. 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.

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.  While our earlier dry weather may have affected us, as of 13 August, nearly all of our growing areas in our eight counties were in the normal range (no drought): NY State Drought Monitor Map

See the attached table for more of the August 20, 2020 results. See the attached pdf for a good guide on corn development and our reference for growth stages.