Most of what little corn has emerged throughout Indiana is in the northern areas of the state. Clear, calm nights with temperatures in the 30's may result in some frost damage to young corn seedlings.
Even though temperatures may not drop below 32oF, frost can still develop on exposed corn leaves due to heat loss to the atmosphere (radiational cooling) on clear, calm nights. Temperatures in low-lying muck areas may actually drop below the freezing mark, causing direct freezing injury to exposed leaves.
As with most early-season injuries to corn, the recovery of frosted corn depends greatly on whether the internal growing point region was damaged. The good news is that the growing point region of corn younger than growth stage V6 (six leaves with visible leaf collars, roughly knee-high) is below the soil surface and protected from above-ground frost damage.
Frosted corn fields need to be left alone for several days after the damage occurs to give them some time to initiate recovery. After three to five days, surviving corn plants should be showing new leaf tissue expanding from the whorls, while dead corn plants will still look dead. Yield loss to frost damage in corn younger than V6 is related primarily to the degree of stand loss, not to the degree of leaf damage.
Frosted corn will turn greenish-black during the first 24 hours, then slowly bleach to a straw color as it dries out. As the frosted leaf tissue in the whorl dries, the whorl will often develop a constricted 'knot' that may restrict expansion of the undamaged whorl tissue later on.
Usually, knotted corn plants will successfully recover as the expanding whorl tissue breaks these knots. Once in a great while, it may be necessary to mow a frosted corn field to cut off severely knotted leaf tissue. The key to deciding whether to mow or not is to allow the damaged field three to five days to show you how well it is recovering.
Return to the the Chat 'n Chew Cafe.
The Corn Growers Guidebook , a WWW resource for corn management systems in Indiana and the eastern CornBelt.
Purdue University Agronomy Extension WWW Home Page.
Purdue Agronomy On-Line! , Purdue's Agronomy Department WWW Home Page.