Growing Degree Days (GDD's) measure crop progress. For more information about Modified growing degree day calculation or where to find Modified Growing Degree Maps, go to Midwest Climate Watch.
You can use use the Crop Degree Day Calculator courtesy of Illinois Climate Network (outlined below) to help predict when corn is going to emerge or calculate the total amount of GDD's accumulated between two dates.
All you need to do:
1.) Select Corn or Soybeans
2.) Select a city on the Illinois map near to your location
3.) Insert the planting date
4.) Press Calculate
The next screen (after you click calculate) will show:
5.) The actual total and average (11 year) of growing degree days (GDD's) at the location that you selection from the planting date entered until present.
6.) Lastly, you are shown one-week and two-week projected totals of GDD's based on site climate totals.
Remember, on average, it takes an accumulation of 70 to 90 GDD's for corn to emerge.
If you want to predict when corn will emerge: In 2014, my Dad's corn was planted on April 19th, near Springfield, IL. Based on the calculations below, I predicted that my Dad's corn would emerge on April 28th, when it actually emerged on April 27th. Only a day off....not too bad! You can also note that the (11 year average) of GDD's at this time (4/19 until 5/3) is 138, but in reality we have actually had a total of 157 GDD's between 4/19/14 through 5/3/14.
If you want to calculate GDD's after emergence: This year, a seed treatment trial was planted in Arenzville, IL (near Springfield, IL). It was planted on March 18th, 2016 and emergence was visible on April 5th, 2016. As you can see below, the actual total of GDD's between March 18th and April 5th, 2016 was 89. The average (11 year) of GDD's was 76.
If you are too busy, let the Burrus COP (Crop Optimization Planner) powered by MyFarms™ help you track and audit your field history, disease and pest susceptibility warnings, Gray Leaf Spot tool, and notifications for things like emergence, silking, and scouting dates. The plans that you execute during the 2016 planting season will need to be converted to Planting Records. For a brief guide on how to convert plans, click here. Converting the executed plans grants you access to a host of additional benefits aimed at helping you achieve maximum yield success.