Corn Development and Temperature

Every thought about this year would say it has been cooler than normal. Our memory and perception can sometime be a bit cloudy when we start looking at the data. Yes the corn crop is behind last year, no doubt but the reason is planting date rather than Growing Degree Day (GDD) accumulations. A good data source that is convenient to use for GDD accumulation is the weather station at the Northwest Agricultural Research Branch the data base is easy to use. I looked at 2007, 2008 and 2009 GDD accumulation from April 1 to 7/26/09 and May 15 to 7/26/09.

GDD Accumulations from April 1 or May 15 to July 26 of 2007, 2008 and 2009 at Northwest Agricultural Research Station, Custer, OH.

Time Period	2009	2008	2007
April 1 to July 26	1717	1704	1744
May 15 to July 26	1445	1456	1482

Surprising is that GDD accumulations are very similar for the past three years given the same time period. Another good source of GDD accumulations is the Ohio Crop Weather Report which as of July 26th had Northwest Ohio only 102 GDD behind average since April 1. Really the big difference is planting date. We probably had 40-50% of the corn crop planted during the period May 15 to May 30 in this growing season.

A cool season has pros and cons that have been discussed in articles by both Dr Peter Thomison, Ohio State University Extension, Corn Specialist and Dr Bob Nielsen, Purdue Extension, Corn Specialist. Click on the specialist name to see their articles.

Basically the pro's of a cooler season are:
Good for pollination
Good for grain fill
Slow disease development

The con's are:
Slow development meaning wetter corn potentially at harvest
Silk balling where silks to not emerge from husk as normal affecting pollination

A warm late August and Early September would help in advancing corn to dry down and lower our drying bills.