Thursday, September 4, 2014

Growing Concern about Growing Degree Days and the Corn Crop

Will we accumulate enough GDD to finish the corn crop? People are a bit concerned and talking about corn development - will it make it, will we have to dry most of the corn crop, etc.? I put an article together in 2009, comparing it to another cool year, 2004. In pulling that chart forward, adding 2014 and a long term average, 2014 doesn't look too bad for heat unit accumulation in southeast Minnesota (Rochester data).  We had a cooler than average July but a warmer than average August.  However, the issue is planting date.  Corn was planted in May this year, much after mid-May.  Delayed planting was also the problem in 2009.  We lost those early season heat units, at least a months worth, by not being able to plant in April.  Considering a May 15 planting date, we are at ~2100 GDD as of Aug 31.  For most corn grown in our region, we need around ~2400 GDD to reach black layer.  An average September (415 GDD) could do that for us, but corn at black layer is still 32% moisture. We will also need a nice October to help dry the crop.

For more information on corn drying and storage, check
NDSU Extension's Grain Drying and Storage (Kenneth Hellevang) website at: http://www.ag.ndsu.edu/graindrying

One last point - the accumulation of heat units around the state, planting and growing conditions have certainly not all been the same.  A good site to "check the numbers" in your location is at the Minnesota Climatology Working Group, Custom GDD: http://climate.umn.edu/cropddgen/cropddgen.asp


Growing Degree Days (Corn) for May through September






Lisa M. Behnken, UM Extension Educator, Crops
Rochester, MN

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