The cold weather over Easter weekend, some cool nights in mid-April and a host of other factors that occurred in individual fields have some growers wondering about replanting corn.  Replanting decisions are generally straightforward based on the yield potential of the reduced stand and the cost of replanting.  Based on plant population and yield response data from over 200 sites in Virginia, if the current stand is 85% or greater of what was intended, it generally does not pay to replant.  But what about filling-in a weak stand rather than killing all the existing plants and replanting the entire area?  Filling-in is of limited benefit unless the surviving plant population is less than one half of what was intended.  IF you can fill-in within 2 weeks of the original planting and IF you can get relatively uniform plant spacing within the row between the old and new plants yields will be similar to those from a uniform-emerging replanted stand.  The biggest problem with this approach is that within 2 weeks of planting, it is probably too early to determine what the final stand will be (and whether patching will be needed).  Once we get to 3 weeks after the initial planting, yield potential is about 10% less with this fill-in scenario than if the entire area were replanted.  Later emerging plants cannot compete effectively with the remnants of the original plant population for sunlight, water, and nutrients.