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Mississippi corn crop marked by Easter freeze

To optimize production, Mississippi corn farmers like to plant early. This year, there were many early optimizers.

“Corn planting during March went very well,” said Erick Larson, Mississippi Extension corn and wheat specialist, at the recent Delta Research and Extension Center field day in Stoneville, Miss. “March weather conditions allowed us to plant early. It didn’t rain much that entire month, which is abnormal. And we had warm conditions that encouraged corn to emerge quickly and get off to a good start.”

Some 88 percent of the state’s corn crop was planted before April 1. Normally, less than half the crop is planted by that date.

And the corn acreage was very large. The National Agriculture Statistic Service (NASS) estimates Mississippi corn acreage this year at 980,000, the largest corn crop in the state since 1960. In fact, this is the first year since 1958 that corn acreage is more than cotton.


“One of the first curveballs thrown to us was the Easter freeze. There were several days when temperatures dipped below freezing and killed all the above-ground leaf tissue.”

Most damage was north of a line from near Clarksdale towards Noxubee County in east-central Mississippi. The farther east one traveled, the cooler the temperatures.

“That was a blessing for a lot of corn (not in the freeze zone), particularly the corn in the south Delta that was planted in late February and early March. Corn there had grown large enough that its sensitive growing point was above the soil surface, making it very vulnerable to freeze damage. It could have sustained direct damage from freezing temperatures.”

However, in corn yet to reach the six-leaf growth stage (about 12 inches tall), the growing point is still underground, close to the plant’s crown.

For much of the corn crop, “the freeze didn’t kill the plants outright. We thought much of the corn should be able to recover. Some did, some didn’t — it all depended on environmental conditions.

“I don’t know how many of you have sprayed liquid nitrogen on top of corn when it’s less than a foot tall. But the freeze event was very similar. It basically killed aboveground leaf tissue.

“Normally, when leaf burn occurs from pesticide applications or environmental events, we don’t have to worry about cool temperatures holding the growth of corn back. Unfortunately, after the freeze we had very cold temperatures for nearly two weeks. That meant the corn had very little growth and ability to recover. Even the corn south of the freeze line grew very little because the heat unit accumulation provided during that two weeks was equivalent to only about two normal days.”

Sunny, again

Nearly two weeks after the freeze, “we finally had several consecutive sunny days which warmed the soil and stimulated corn growth. Some corn recovered very well. Some didn’t recover at all.”

There are two main reasons corn didn’t recover.

“First, if the above-ground leaf tissue is frosted off, the plant doesn’t have the ability to photosynthesize and produce energy for itself. It has to rely on the energy reserves in the seed until it gets warm enough to generate new leaf tissue.

“Unfortunately, a lot of corn after 10 to 14 days began to turn brown and rot. We think that may be associated with secondary bacterial infection because plants weren’t growing for so long. Basically, the same organism that rots lettuce in your fridge may have caused damaged corn plants to rot.”

One thing Larson and colleagues noticed was the field’s culture often affected crop recovery. Where there was substantial crop residue, “the soils were likely cooler and wetter. That slowed plant growth and likely promoted bacterial infection, promoting more stand loss in areas of the state with freeze-damaged cornfields.”

Twisted whorl

In late April, twisted whorl syndrome showed up south of the most freeze-damaged area in the state.

“This phenomenon was closely correlated to the extreme temperature fluctuations around Easter weekend causing physiological problems in random plants. New leaves in the whorl became tightly wrapped and twisted, instead of emerging naturally. When such plants popped out of that tightly wrapped whorl, the leaves were initially yellow because they weren’t exposed to sunlight during the time the whorl was wrapped.

“These plants came out of the ground quickly prior to the cold period … it was like the plants pulled the emergency brake when driving 30 mph. Then, when it warmed up, the plants began growing again and had problems — an abnormal reaction to widely fluctuating temperatures. The plants generally grew out of the problem quickly and didn’t have many long-lasting effects.”

Going into the season, Larson was worried about drought conditions based on soil moisture levels. On a drought-monitoring map, Larson pointed out “the red, or drought-stricken, area begins at the Mississippi River and extends east. The area in east central and northeast Mississippi is also largely red. The red areas represent rainfall over the last six months at less than 50 percent of the norm. So we’ve had extremely dry conditions for the last six months.”

The dry conditions caused corn irrigation to begin “earlier than I can remember. There were a lot of center pivots beginning to run in late March to get the corn out of the ground. Many irrigation systems began before the freeze event.”

Mississippi’s corn yields will reflect rainfall conditions in the state. “We’ve had very little soil moisture reserve to carry the crop.”

Dryland corn will be hurt significantly, particularly in the east-central and northeastern parts of the state. The irrigated crop “looks good, for the most part.”

Recent rains “will certainly help take irrigation termination management decisions out of the equation, except for the northernmost areas of Mississippi, or if the corn was late-planted or replanted. There’s still corn in the north Delta and replanted corn that’s a good 20 to 25 days away from physiological maturity. But most of the March-planted corn should be reaching physiological maturity (by the third or fourth week of July).”

Mississippi corn farmers have had recent problems with root lodging. Root lodging often occurs at this time of year primarily because the corn plant is heavier now than it will be at any other time. “The ear is as heavy as it’ll get. The stalk and leaves are still full of moisture.

“Couple all that with soggy soils and wind and it may lead to root lodging. There’s no way around that. As the plant dries down, the potential for root lodging drops.

“As we get into August, the problem becomes stalk lodging. That’s where the stalk collapses above the soil level.


There was also a lot of freeze damage to Mississippi’s wheat crop. “It severely damaged a lot of the crop that had headed, or was beginning to head.”

In the north part of the state, wheat yields ranged from a total loss to 85 bushels per acre. South of the freeze zone, “we had probably our best wheat yields ever — lots of farms averaged in the low 70-bushel range. Lots of folks were cutting 60 to 80 bushels. The NASS average had us pegged at 61 bushels per acre, a new state wheat yield record.”

The freeze damage closely related to crop maturity. The closer the wheat was to heading, the more damage. Larson said two management factors affected that: early planting and early-maturing varieties. “Early-maturing varieties, particularly if planted (before mid-October), experienced severe yield losses.”

Larson said MSU wheat variety trial data is now available on-line. The printed version should be available in a few weeks.

What does Larson see happening with corn and wheat in 2008? “Our guess is corn acreage will remain even or decline somewhat. A lot of that will be determined by how harvest goes. There’s definitely a lot of interest in wheat for next year. That interest is across the Mid-South.”

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