Well, I know the topic is on most of our minds so we might as well start discussing it; "Delayed planting and when do I switch maturities?"  When I started putting together this update I began gathering all the average Growing Degree Day data and average 10% chance for a first frost date for the three state area.  Then I began to dig up past university newsletters covering the topic.  As I read them, I realized that at least right now it is still pretty early to consider switching maturities.  Here are a few quotes:

Bob Nielson, Purdue University "Based on research conducted by myself and Peter Thomison at the Ohio State University, there is little reason to switch from normally adapted hybrid maturities to earlier ones until at least the early part of June.  Corn hybrids appear to somehow adjust to delayed planting by flowering later and maturing in fewer heat units than corn planted on time."   Originally published in Purdue Pest and Crop newsletter 5/5/95

Pete Thomison, The Ohio State University "Don't worry about switching maturities unless planting is delayed to late May.  If planting is possible before May 20th, plant full season hybrids to allow them to exploit the growing season more fully" The Ohio State University C.O.R.N. newsletter 5/6/02

Emerson Nafziger, University of Illinois  "When do I switch to an earlier hybrid?  In Southern and Central Illinois, most first choice hybrids are not extremely full season.  The supply of accumulated …GDU's is more than adequate to meet the needs of these hybrids.  Most popularly grown hybrids can be planted into early June in the Southern half of the state and still be expected to mature before frost.  In the Northern part of the state, seasonal accumulations are lower, but many of the first choice hybrids are the same as those in Central Illinois, meaning that they are less likely to receive adequate GDU's if they are planted late.  In the northernmost counties, where full season hybrids would generally require about 2,600 GDU's, such hybrids should be replaced with earlier hybrids if planting is delayed past May 20-25 or so.  Such a switch is not necessary in the central part of the state until after May 31st and perhaps not even then."  University of Illinois Crop extension newsletter, May 8th 1998

One point I want to emphasize is something Bob Nielson discussed and that is new research that suggests later-planted corn somehow adjusts to delayed planting and matures in fewer days than when planted normally.  The cause of this phenomenon is still undetermined.  Some suggest it is a response to day length.  I don't think anyone knows for sure, but to quantify it for you, this research suggests that "a typical corn hybrid's GDD requirements decrease about 5 GDD per day of delayed planting from late April-early May through at least the early part of June.  This means that a 30 day delay in planting may result in a hybrid maturing in 150 fewer GDD (30 days X 5 GDD/day)."  The bottom line is that later-planted corn adjusts and matures quicker.

If planting is delayed past the end of May, I will send some information on switching hybrids.  Until then, it appears all the best advice says to "Stick with what you have for now."  If, for other mitigating reasons you do want to consider switching (no dryer for instance), feel free to contact me to discuss your situation.  I have included some links to the newsletters I quoted and other information you may find of interest in regard to this topic.  As always, call with questions at 1-800-240-0101 or drop me an email at jschwartz@icorn.com.

Switching to Earlier Hybrids - Purdue 1995  

Delayed Corn Planting and Hybrid maturity Switching - Purdue 1995

Wet Again: Corn Planting Delays - University of Illinois 1998

Crop Observation and Recommendation Network - The Ohio State University 2002