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College of Food, Agricultural, and Environmental Sciences


Cold Snap Raises Concerns Over Corn Crop

April 26, 2005

COLUMBUS, Ohio — A recent late season cold snap with accompanying freezing rain and snow has Ohio corn growers questioning the fate of their newly planted crop. But Ohio State University agronomists say the crop is tougher than most would believe it to be.


"In regards to the freezing event, I think that the chances for recovery for corn are pretty good," said Ohio State University Extension agronomist Peter Thomison. "The lethal effects of freezing temperatures are usually not a major issue for us. We've had similar conditions in past years and came out of those problems with little damage and pretty good yields."

Warm, dry weather the past several weeks has driven corn producers to the fields. With over 70 percent of the corn already planted in many areas and the remainder half-planted, it could very well be the earliest that the corn crop has been established.

Agronomists generally downplay the impact of low-temperature injury in corn because the growing point is at or below the soil surface, thereby protecting it from air temperatures. Additionally, the plant's cell contents can act as an "antifreeze," protecting plant tissue from temperatures as low as 32 degrees Fahrenheit.

"Probably a greater concern to us is how long soils remain saturated," said Thomison. "If we get periods of cloudy conditions that prevent drying out and the soil remains saturated, then we are probably opening the doors to seedling blight problems."

Said Pat Lipps, an Ohio State University plant pathologist with the Ohio Agricultural Research and Development Center, "Cold temperature injury can play a significant role in predisposing plants to root infection and blight. Under normal conditions plants can continue to grow and produce new roots, but when other injuries occur, new roots cannot develop rapidly and Pythium and other soil fungi can kill stressed plants."

Additionally, excessive rainy weather can cause problems to already damaged corn, said Lipps.

"Bacterial soft rots can destroy the corn growing point," he said. "If growing conditions are favorable, the plants typically outgrow bacterial damage. But if weather remains cold, wet and cloudy following the freezing event, the potential for bacterial damage increases."

Freeze-damaged corn plants may also suffer cosmetically from a twisted whorl condition. Thomison said that the freezing conditions prevent the leaf from unfurling normally, resulting in a tied leaf whorl.

"The damage resembles the tight leaf rolling often associated with herbicide injury," said Thomison. "But the plants tend to outgrow this condition when growing conditions improve."

Though it's too early to tell what damage, if any, has been caused from the cold temperatures, growers can evaluate the seedlings or the newly germinated plants to determine the extent of any damage. Thomison said that mushy seedlings or rotting growing points are a sign of potential seedling blight problems. The solution to such a situation is to replant.

The unusual weather that could give growers problems with their crop was the result of storms that blew through Ohio over the weekend, dumping as much as a foot of snow in some areas and producing freezing rain and freezing temperatures throughout the state.

Ohio corn growers begin planting in April, sooner or later, depending on the weather.

"Growers have to plant when the growing conditions are favorable," said Thomison. "Long-term historical data in Ohio shows that during the optimal planting time there is about one day out of three when field work can occur, and this varies depending on soil drainage. Because it's so wet during this time of year, growers took advantage of the favorable conditions to plant and now they may have to wait a couple of weeks to find out how the plants have responded to these most recent weather conditions."

For latest updates on crop conditions, log on to Ohio State University's Agronomic Crops Team Crop Observation and Recommendation Network (C.O.R.N.) newsletter at

Candace Pollock
Pat Lipps, Peter Thomison