Scott Fullen says he considered planting cotton on ultra narrow rows in the late 1990s and the early 2000s but decided against it because of the discounts merchants were assigning stripper-harvested cotton.

So when Fullen and his family heard about a new harvesting system that could spindle pick cotton in 15-inch rows, they “jumped at it” on 900 acres on their farming operation near Ashport, Tenn.

That was in 2004. Their success with 15-inch cotton, which Scott Fullen reported on at the 2005 Beltwide Cotton Conference in New Orleans, has attracted the attention of other producers and of university scientists conducting research on 15-inch cotton. Some estimate growers grew 40,000 acres of 15-inch cotton in 2006.

The idea of planting cotton on 15-inch rows continues a trend toward narrower row spacings in west Tennessee, says Owen Gwathmey, an agronomist with the University of Tennessee Agricultural Experiment Station in Jackson.

“A lot of 30-inch cotton is grown in west Tennessee where we tend to have more hill ground and thin soils,” says Gwathmey. “We typically don’t grow a tall plant that closes the canopy as quickly as we would like on those soils.”

Speaking at a 15-inch Cotton Field Tour stop at the Fullen Land and Management operation in the Tennessee Delta, Gwathmey said the 15-inch planting system could be a good fit for west Tennessee growers who, like cotton producers everywhere else, face tight profit margins.

“We think we’re picking up the pluses of ultra-narrow-row cotton without the minuses,” says Gwathmey. “You don’t get the extraneous leaf material with a spindle picker that you do with a stripper harvester, and you don’t necessarily need a short plant the way you do with a finger stripper.”

And the costs seem to be lower for 15-inch cotton, for which, university research shows, optimum yields can be achieved with 60,000 to 65,000 plants per acre versus 80,000 to 100,000 per acre in ultra narrow rows.

“When you get up around 100,000 seed or more per acre with a grain drill in ultra-narrow-row cotton, the seed costs go through the roof,” says Gwathmey. “And row planters (in the 15-inch cotton) are more precise, so plant stands are more uniform.”

Gwathmey and Jerry Parker, Extension director in Lauderdale County, Tenn., reported on research being conducted on ultra-narrow-row and 15-inch cotton at the University of Tennessee’s Milan Research and Education Center during its biennial No-Till Field Day.

Researchers have been planting 25,000 to 50,000 seed per acre in the 38-inch to 40-inch conventional rows, less than 80,000 seed per acre in the 15-inch row spacings and more than 80,000 seed per acre in the 7.5-inch to 10-inch spacings. (The plant population has been closer to 60,000 to 65,000 in the 15-inch spacings.)

“We had 2.5 seed per foot of row in the 15-inch cotton and 4 seed in the 30-inch cotton in 2005,” Gwathmey said. “That seeding rate is too high, but we wanted to make sure we got a stand in the first year.”

In 2005, researchers planted 15-inch and 30-inch cotton in solid and skip-row patterns in two similar fields at the Milan Research and Education Center. One field was pivot irrigated and the other was not.

The agronomists planted small, replicated plots of Deltapine 444 BG/RR in the two row widths in a solid planting, a 2+1 skip-row and a 2+2 skip-row pattern. The plots were planted with a John Deere 7340 planter equipped with finger pickup units.

Under 2005 growing conditions, lint yields were 20 percent higher in the irrigated than in the non-irrigated field, but the relative response to row treatment was similar in the two fields, according to Gwathmey.

Three combinations of row spacing and planting patterns in the UT study produced similarly high yields: 15-inch solid; 15-inch, 2+1 skip row; and 30-inch, solid planting. Lint yield of this group averaged 1,315 pounds of lint per acre, while plant population density ranged from 52,800 to 80,200 plants per acre.

“The highest yield per plant in this group was obtained in the 15-inch, 2+1 skip rows, suggesting this configuration would have a lower seed cost and tech fee than other row patterns that produced equivalent yields,” says Gwathmey. “We’re getting equivalent yields with one-third less seed than in the solid 15-inch rows.”

In 2006, the researchers omitted the 2+2 skip-row pattern and focused on 15-inch and 30-inch rows each planted in solid and 2+1 skip-row. They planted ST 4357 B2/RF cotton with a John Deere 7340 planter equipped with finger pickup units calibrated to plant either 1 or 2 viable seed per row foot.

Seeding rates ranged from 11,600 seed per acre in 30-inch, 2+1 skip-row cotton with 1 viable seed per row foot to 69,700 seed per acre in 15-inch solid cotton with 2 viable seed per foot of row.

Researchers were pleased with the quality of the cotton in each row spacing and configuration in 2005, says Gwathmey. “This crop was knocked down by two different storms — Katrina and Rita — but still produced good grades. Any producer would be happy with what we saw.”

Controlling weeds in 15-inch cotton presents some of the same challenges as weed control in ultra narrow rows, says Larry Steckel, weed scientist with the West Tennessee Research and Education Center.

“We can’t use our hooded sprayers or post-directed rigs in 15-inch cotton,” he said. “We favor Roundup Ready Flex or LibertyLink cotton because we can use over-the-top herbicides to take out the weeds. But we believe applying a pre-emergence herbicide is a key ingredient in providing early weed control.”

Steckel, who also spoke at the 15-inch Cotton Field Tour stop at the Fullen farm, said early season weed control is critical to preventing yield loss in 15-inch and conventional cotton production systems.

“We think a pre-emergence herbicide should get definite consideration,” he said. “Cotoran is the No. 1 pre-emergence herbicide in Tennessee, where about 90 percent of the acres receive a pre herbicide, but Caparol and Prowl also are applied.”

In over-the-top applications, some growers are putting Dual Magnum in with their glyphosate in the Roundup Ready or Flex cotton or Ignite in their LibertyLink cotton. “This can provide residual control for 20 to 30 days. By then, the 15-inch cotton should be giving you shade. Weeds, especially pigweeds, need sunlight to grow.”

Producers can also add Envoke or Staple LX to help control morningglory. “Glyphosate is a little weak on morningglory, and a small amount of Envoke or Staple LX will help on these weeds,” he said.

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