Grain sorghum research will help improve harvest

Frances Gould, LaBauve, Randy  |  10/24/2014 1:44:17 AM

Grain sorghum is harvested at the AgCenter Rice Research Station in Crowley. (Photo by Bruce Schultz)

LSU AgCenter researchers are studying grain sorghum to help improve harvest potential and save farmers money. One set of projects from 2013 focused on validation of recommended planting dates.

Crops were planted on four different dates at three locations – the Dean Lee Research Station in Alexandria, the Macon Ridge Research Station in Winnsboro and the Northeast Research Station in St. Joseph. The recommended planting dates are between April 1 and May 1 for south Louisiana and between April 15 and May 15 for north Louisiana.

"At Dean Lee, late frosts severely damaged the early planted crop," said AgCenter agronomist Josh Lofton.

"Macon Ridge has more drought-prone soils, so the assumption was by decreasing the plant population per acre, we could decrease overall plant competition for crop inputs, including moisture," said Lofton.

The sorghum crop can adapt to lower seeding rates by producing larger, more fully developed heads compared to smaller heads with the higher seeding rates.

The second planting date in mid-April produced the highest yields across all locations; however, the effect of plant population on crop yield varied. The second planting date at Macon Ridge showed populations could be decreased to 60,000 plants per acre – compared to the recommended 75,000 – without significant yield decreases.

The Dean Lee and Northeast crops did not benefit from lower plant populations. "For most of the planting dates, the current recommendations of 75,000 plants per acre appeared to be the correct numbers for the deep, rich alluvial soils of St. Joseph and Alexandria," Lofton said.

2014 crops were planted at the same dates and locations as the 2013 study. It often takes three, four or five cycles of research to gather significant data, said AgCenter agronomist Rick Mascagni.

One of Mascagni’s projects is studying the potential for ratoon crops in grain sorghum. Trials

were conducted at the Rice Research Station in Crowley, Dean Lee Research Station and the Northeast Research Station.

Similar tests were conducted at the same sites in 2013. The best ratoon crop was at the Northeast Research Station, but an influx of blackbirds heavily damaged the excellent crop. The fungal disease anthracnose, brought about by high humidity, also had an effect on the crops, particularly at the south Louisiana sites.

To further evaluate the disease component, the trials were duplicated at each location. The fungicide Quilt was applied to one trial, while another had no fungicide treatment. Insecticides are being applied when needed on all the trials. Researchers will gather data on yield for the main crop and the ratoon crop, while giving disease ratings and determining the influence of disease on the crops.

Whatever disease is in the first crop can carry over to the ratoon crop. "You want to go into the ratoon with a healthy crop. We are trying to maximize yield for both crops by applying the needed inputs," Mascagni said.

This year, he hopes to obtain data to evaluate yield potential and monitor input costs – a key factor in determining the feasibility of ratoon-cropping in Louisiana.

Last year, researchers were analyzing the most effective chemicals to manage populations of insects like headworms and sorghum midge, but the focus shifted to battle a new enemy – sugarcane aphids. These insects became a major problem – the first time they have ever been a pest in sorghum in the U.S., said AgCenter entomologist David Kerns.

"Some farmers lost 100 percent of their crops in 2013, and the norm was a 50 percent loss," he said.

"Our main emphasis this year is sugarcane aphids, which have the potential to wipe out crops throughout the Gulf Coast," said Kerns. "We screened a number of insecticides last year, and none of them worked."

AgCenter researchers identified the nonregistered herbicide Transform as an effective treatment and were granted Section 18 approval from the EPA to help with the emergency situation. It was sprayed on most of the sorghum crops in the state.

"We’re doing more research on alternatives to that product," Kerns said.

Additional insect research includes seed treatments, threshold studies, screening for host-plant resistance and baseline toxicity. Randy LaBauve

This article was published in the 2014 Louisiana Soybean & Grain Research & Promotion Board Report.

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