Early-planted corn and cold weather
When folks worry about the effects of cold weather on corn, they often fail to distinguish between simple frost events and lethal cold temperatures. Frost can occur at temperatures easily up to the high 30's F, but lethal cold temperatures for corn are generally thought to be 28F (-2C) or colder. Air temperatures in recent days have certainly dropped to 28F or lower in areas of the state. Whether such cold temperatures "penetrated" the upper inch of soil near the growing point region of corn seedlings is not clear, but may be possible in fields where soils are excessively dry and free from surface residue.
Only time will tell whether this week's cold temperatures and frost will cause permanent damage or death of early-planted corn around the state. Recovery of damaged plants will usually be evident within 5 to 7 days following such events. Come October, we will know for certain whether this year's early planting risk takers will have "won the game" or not.