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Hill and Furrow

Following Crop Development in a Corn Planting Date Trial

You might have always wondered whether there was some way to estimate when your corn crop is likely to reach the silking and black layer growth stages. Well you might just be in luck if you gather the following information about a particular corn hybrid (when it was planted, where it was planted, its estimated days to maturity) and use any internet browser to visit Useful 2 Useable' s free corn degree day decision support tool.

I spent some quality time this morning scouting for cutworm injury in fields at the Northwestern IL Ag R&D Center. One field was planted to a 108 day hybrid in a corn planting date x fungicide trial. After counting leaf collars and taking a couple of pictures, I was able to plug in the location data (Monmouth) and days to maturity (108) into the decision support tool to estimate when silking and black layer growth stages are likely to occur (Figures and Table). I could also compare the beginning of 2017 to 2016 and years in which growth was a little bit more accelerated than normal (2012) and a little bit slower than normal (2013). This comparison showed that growing degree day accumulation for the April 11 planted corn is similar to 2012 (380) and ahead of both 2013 and 2016 (Figure).

Table. Planting dates and days after planting, accumulated growing degree days and growth stage on May 18 along with projected silking a maturity dates for corn in a planting date x fungicide trial at the Northwestern Illinois Ag R&D Center in Monmouth

On May 18

Projected ______ date

Planting Date

Days after planting

Accumulated GDD

Growth stage



April 11




July 9

Sept 3

April 24




July 15

Sept 11

May 9




July 19

Sept 17

As this decision support tool costs nothing but time it might be worthwhile to check it out on the next rainy day.