Making a replant decision after frost can be challenging. Which plants do you include in population counts, when evaluating a damaged corn stand? In 2012 a hard freeze hit the Corn Planting Date Study here at the CSREC, we took that opportunity to tag plants with different levels of damage and follow them to harvest. The bottom line is, if you don't see more than a hint of green after 5-7 days, it is a weed. If the whorl shows real elongation even if leaves are gone it should be OK and included in a population check. The attached slides are part of a presentation I made on the results.