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Louisiana corn, grain sorghum and soybeans in early harvestLouisiana corn, grain sorghum and soybeans in early harvest

David Bennett

September 7, 2007

6 Min Read

At an estimated 93.5 million acres, the U.S. corn crop is massive. And Louisiana's portion of that acreage will likely be one for the record books.

“We're cutting Midwestern-type corn yields, which is unheard of,” said David Lanclos, LSU AgCenter corn, milo, and soybean specialist at the recent Dean Lee Research Station field day in Alexandria, La.

“This is largest Louisiana corn crop ever. USDA is predicting a record yield and I agree. If you look at the numbers consistently being brought into the elevators, the yields are 170 to 220 bushels statewide, even in dryland situations.”

Lanclos listed four reasons the Louisiana corn crop is so good:

  • The crop was drought-stressed early. “I'm a big advocate of drought-stressing a crop early. When that happens, it makes the root systems go deeper and forces it be more effective.”

  • Cooler temperatures during pollination. “We normally have intense heat during pollination. This year, the temperatures were much cooler and that allowed the corn plants to fertilize from the bottom to the top.”

  • A light insect pest year.

  • Luck on timing, Mother Nature smiles. “Four weeks ago, we were talking about the potential damage all the rain would do to the corn crop. I was very worried. Now, approaching corn harvest with a 105-degree heat index is great. The only drawback is the corn is drying down so quickly we don't have the ability to get it to the elevator.”

USDA estimates Louisiana farmers planted about 225,000 acres of grain sorghum in the state. That's up from about 85,000 acres last year.

The main reason for the big increase is price. “Sorghum prices went above $3. When a commodity like grain sorghum starts at $3, it becomes a lot more attractive than it is customarily.

“Right now, yields are very strong. It doesn't appear we'll set a state yield record this year, though. USDA predicts we'll hit 93 bushels per acre. Last year, the average was about 99 to 100 bushels — we had a lot of 120-bushel fields.”

Lanclos says there are several reasons the state won't see a 100-bushel yield this year. Number one is rainfall. While it requires water to make yield, grain sorghum is essentially a dryland crop. While the rains helped other crops, sorghum didn't need the amount of rainfall received in many parishes.

Because of the excess rainfall, “several diseases came in. Those diseases — anthracnose and fusarium head blight — are traditionally here but not to the levels we saw. Many have walked bright red sorghum fields where heads were falling over. A lot of that wasn't from sugarcane borers, but from anthracnose.”

Anthracnose was more prevalent in sorghum fields following sorghum. “I'd point out how important crop rotation is. I fully realize the markets are driving what we're planting in 2008. A lot of producers have already booked commodities for 2008 and 2009. But please try some effective crop rotation. We need to get past planting the same crop in the same field year after year.”

Late-planted grain sorghum usually isn't a good idea, but plenty of Louisiana growers tried it this year.

“I'm concerned about yield potential in that late-planted crop. I've seen a lot of fields with yields anywhere from 40 bushels to 60 bushels per acre.

“One landowner told me, ‘I don't care if I cut only 50 bushels because I don't have a lot in the crop.’ I said, ‘That's a valid point. But if you look at it from an IPM strategy, there are sugarcane borers, other borers and midges and you're causing problems for your neighbor as well as yourself next year.’”

For the first time in a long time, soybeans lost Louisiana's top spot in total acres planted. This year, the state has about 625,000 acres of soybeans, a reduction of 23 percent from last year's 840,000 acres. “That isn't very shocking considering how dramatically corn acreage rose.”

Currently, less than 15 percent of the state's soybeans have been harvested. But the early beans have left Lanclos “very optimistic because we're running 55 to 60 bushels. That's a bit stronger than is customary.”

USDA is predicting a state soybean yield record of 37 bushels after last year's record 35-bushel average. While optimistic the state yield will be in the “strong 30s” Lanclos is less certain about hitting 37 bushels. “We'll have to cut a tremendous amount of good beans to get to 37 bushels.”

The reason for Lanclos' concerns: about a third of the state's acreage is in a wheat double-crop system. Three weeks ago, when it quit raining, those beans were approaching R-5, the beginning of seed fill and the most critical time a crop can be moisture-stressed.

“Because of that, R-5 will last about four weeks. We'll go another week of no rainfall and that will mean the beans will suffer.”

Another thing of interest since early August is what's happening in the upper third of the canopy. “Keep in mind the heat we're dealing with; the heat index is probably at 104, right now. Soybeans can sustain a lot of heat and pressure. But when faced with consistent heat for almost three weeks, there will be problems.”

Already, there are many scalded beans. “We're still applying fungicides, insecticides and, in some situations, late herbicides. We're putting all that stress on the crop and we're seeing a lot of mottling in the upper canopy.”

On top of that, there's some three-cornered alfalfa hopper damage. Many soybean plants have girdling around the petioles. Add the insect damage to the other stresses, “and that's why these symptoms are showing up. Many growers think the problems are due to SDS. Others say it's stem canker, or many other things.”

During the third week of August, Lanclos began getting calls from producers who had hauled grain to the elevator. “I don't usually make comments about elevators because once it leaves the farm gate, it isn't a lot of my business. But from a pure physiology standpoint, there are a couple of questions that keep popping up. We're seeing a lot of our crop — and I know Mississippi and southeast Arkansas' are the same — being graded carefully at the elevator.”

The yellowed surface of the beans looks fine. When split open, however, the inside of the beans are greenish.

After consulting with physiologists and specialists, “we came up with a solid conclusion about what's going on. In the absence of disease pressure — cercospora leaf blight, aerial blight and others — the plants are prematurely drying down due to heat stress.

“What's happening hormonally in the seed is the oils and proteins are being suspended. The plant is dying prematurely in the upper third and because of that, even though the crop looks phenomenal, the elevator will dock 10 percent. Unfortunately, there isn't a solution. It's across varieties and planting dates.”

About the Author(s)

David Bennett

Associate Editor, Delta Farm Press

David Bennett, associate editor for Delta Farm Press, is an Arkansan. He worked with a daily newspaper before joining Farm Press in 1994. Bennett writes about legislative and crop related issues in the Mid-South states.

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