Average daily low air temperatures over the past mornings have ranged from 22F to
28F throughout a large area of
Conventional wisdom (or agronomic legend) says that corn seedlings will tolerate air temperatures down to about 28F before serious injury occurs. One caveat to this statement is that soil temperature typically changes less dramatically than air temperature, thus delaying the onset of cold-injury to the plant’s growing point region while it remains below ground. Moist soil will change temperature more slowly than dry soil, thus “insulating” the growing point further from the onset of cold-injury.
Nevertheless, the risk remains for injury to early planted
corn in southern
Depending on the severity of damage, visual symptoms may not be evident for several days to a week after the occurrence of the potentially lethally cold temperatures. Don’t worry so much about damage to above-ground leafy tissue as to the potential for injury to the below-ground growing point. Appearance of the growing point region plus visual evidence (or not) of fresh leaf tissue from the damaged above-ground whorl will be the key diagnostics for assessing condition of the stand of corn.
Corn planted, but not yet emerged may eventually exhibit what is often termed “cork-screwed” elongation of the mesocotyl or coleoptile during emergence in response to chilling injury to the cell tissue of those plant parts (Nielsen, 2004b). The worst case scenario in this situation is failure of affected seedlings to emerge; instead leafing out underground.
As with many replant decisions, patience is the key word (Nielsen,
2006). Damaged fields usually need to be given several days to a week to
begin their recovery before one can confidently assess their condition and the
potential need for replant. The
Corn & Soybean News. Apr 2007. Corn Replanting Issues.
Nielsen, RL (Bob). 2004a. Growing Points of Interest. Corny
Nielsen, RL (Bob). 2004b. Corkscrewed Corn Seedlings. Corny
Nielsen, RL (Bob). 2006. Corn Replant Decision-Making. Corny
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