Whatever you planned on doing this coming Tuesday make sure you carve-out enough time to look at corn fields.  September 1^st is a benchmark date for evaluating the status of corn maturity and making a realistic assessment of final utilization.  Normally, we like to see corn fully dented by September 1^st to be confident that grain maturity (black layer) will be reached.  In 2009, fully dented corn by 9-1 is not going to happen, so let's start working backwards from there.  If grain kernels are just starting to dent (and there won't be much corn in this situation either), it will take about 28-30 days to reach black layer.  Given an average frost date of around October 5th-10^th, early dent corn probably will make it to black layer and definitely should reach ½ milk (silage stage).  If corn kernels are still in the milk stage, and lots of acres will be, we can figure about 40 days to black layer.  Hence, we will need at least average heat units in September and early October plus a normal killing frost date or later to get milk-stage corn mature.  It should easily make ½ milk stage unless we have an unusually early frost.  Any corn that is in the blister stage or earlier has little or no chance of reaching black layer and needs to be targeted for silage. 

Here is Rankin's assessment of probability based on corn maturity on September 1st:

Killer or not?
     It's important to keep in mind that not all frosts are created equal.  A frost that kills leaf tissue but not the stalk will still allow for transport of nutrients and water to the kernel.  However, some yield reduction may still occur because of loss of photosynthetic leaf tissue.  Sometimes, when the plant senses that the end is near, the black layer may develop pre-maturely even though stalk tissue is still functional.  Of course a hard killing frost will bring everything to a grinding halt. 

Why are we in this mess?
     The answer is quite simple:  it's been a cool summer.  How cool?  Since I've been tracking such things beginning in 1997, this year was only exceeded in "coolness" by 2004.  As of August 25^th, the amount of heat accumulated this year (1734 GDU's) would "normally" be reached around August 4^th or 5^th.  Further, in the above average heat years of 1998 and 1999, the same number of GDU's was reached a full month earlier.