As most corn producers know, there is always that point in time where the advantages of planting a full season hybrid (97 to 100 day relative maturity) diminishes to the point where shifting to a shorter-season hybrid will generally result in drier corn and higher yields come fall.  For south-central Wisconsin, we reach that point about May 20.  The next break point comes about June 1 when shifting to an ultra-early corn hybrid is needed to reach grain maturity.  By June 10^th, grain yield is reduced to 50 percent of a full season hybrid planted in early May and the economics of planting corn for grain falls somewhere well below marginal. 

     So-called “switch dates” are not static.  Both corn price and drying costs impact when these days actually occur.  Higher corn prices delay the switch date, whereas higher LP gas prices make it desirable to make the conversion earlier.   

     Corn that is planted for high moisture grain or silage offers a bit more flexibility in terms of acceptable planting date to reach economic yields.  However, the flexibility is driven only by the fact that fields stand an increased chance of reaching desired harvest maturity.  Expect significant yield declines with late and ultra-late planting dates.  For corn silage, overall feed quality also declines as planting dates are pushed into late May and June.  This is the result of a decreased grain:stover ratio. 

     When deciding at what point to make a shift to shorter-season hybrids, your ability to accept risk becomes an important factor.  Here are some pertinent questions to ask yourself:  "Can I afford significant drying costs this fall?", "Do I have the option of harvesting or selling a portion of my crop as silage or high moisture grain?", "How important is it that I complete fall tillage in a timely manner?", and "Can I easily switch to a top performing shorter maturity hybrid?"