Is Corn Susceptible to Spring Frosts?
Corn in the V5 stage (five leaves with full collars showing) or less will recover from light frosts because the growing point is still below the soil surface. Symptoms of frost damage will start to become visible about 1-2 days following a frost event. Symptoms mainly involve the appearance of water-soaked leaves that eventually turn brown and necrotic. Frost will often kill young corn leaves, but even plants with extensive leaf damage will likely recover if the growing point was not injured. The death of leaf tissue above the growing point has only a small effect on corn growth and yield at early stages of development, though it is known to delay plant growth by a few days for the plant to recover.
If air temperatures drop to -2 C or less for more than a few hours, the growing point can be injured or killed, even if it is still below the soil surface.
To assess corn plants following spring frost, let the plants recover for 3-5 days prior to scouting. By this stage, surviving corn plants should have new leaf tissue expanding from the whorls. Note that it is not unusual for new leaves to get caught up in the dead leaf tissue, which could further delay the plant in maturity. Check the growing stage during this scouting session as well. Pull up the entire plant, including roots, and split the plant lengthwise. A healthy growing point is white or creamy in appearance, and a damaged or dead growing point will be soft and greyish with a water-soaked appearance and no new growth from the whorl.