By Michael Plumblee
As many of you know, temperatures across the state did drop below freezing last night (3/16) and will again tonight (3/17). I have not heard any reports of temperatures dropping to 28 F or below yet, but Northern SC could very well have seen those temps. If you think your area experienced sub-freezing temperatures and you have corn seed in the ground or corn that has emerged, wait 5-7 days after freezing weather to assess corn stands and mortality.
If you are scouting immediately after the freeze event, you may not see visual damage or injury; it will take some time for the plants to show visual symptoms. After the 5-7 days of waiting, you should then be able to tell if the corn will recover. This would mean you would be seeing new green growth in the whorl of the young plants. If you are not seeing new green growth in the whorls by this point (5-7 days after the freezing temperatures), the plants may be dead, and replanting may be warranted at that point.
Based on data I have reviewed from other universities, if corn is recovering, we should not see a yield loss associated with the freeze injury experienced by the young plants, even if all above-ground foliage was killed off. If there is a particular field or area that experienced lower temperatures and plant death occurred, I would encourage you to scout the entire field and evaluate the surviving stands to determine if a total replant of the field is needed or if spot replanting could be done. There are exceptions: “buggy-whipped” seedlings with green whorls may struggle or fail to unfold, causing severe stunting. In those situations, a replant may be warranted.
Source : clemson.edu