Georgia cotton crop is near-record

Vastly improved yields were offset by low prices and continuing concerns about quality as Georgia cotton growers produced a near-record crop in 2001.

“We saw better yields in 2001 than in the recent past, but this was tempered by low prices,” says Phil Jost, University of Georgia Extension agronomist. “There's also the issue of fiber quality, which reared its ugly head again this past year.”

Georgia cotton producers planted about 1.5 million acres in 2001, reported Jost at the recent Georgia Cotton Production Workshop in Tifton. “Nearly all of that was harvested, with growers averaging about 685 pounds of lint per acre. We expect to gin about 2.2 million bales. As these numbers indicate, yields were much improved over 2000,” he says.

Much of the credit for the considerable boost in yields goes to timely rainfall, he adds. From May 1 through the end of September, rainfall amounts in Georgia were up substantially compared to the rainfall recorded in 2000.

“We're still not quite up to the normal average in certain regions of the state. Rainfall in 2001 was much less in Statesboro and other parts of east Georgia than in the southwest portion of the state,” says Jost.

Most Georgia cotton producers favored three varieties in 2001, notes the agronomist. Deltapine 458 with the stacked Bt/Roundup Ready gene accounted for 20 percent of the state's crop. Deltapine 5415 and 5690 Roundup Ready varieties made up about 15 percent each of Georgia's total cotton crop. Less than 5 percent of the state's fields were planted to any other one variety.

There were marked increases in the amounts of stacked gene and Roundup Ready cotton planted in Georgia in 2001, says Jost, while the amount of Bt cotton acres planted decreased. In addition, there was a further drop from the previous year in the amount of conventional varieties planted, he says.

Turning to fiber quality, Jost says Georgia's 2001 crop is averaging about 34 in fiber length. “This is an improvement over the past couple of years, but it's nowhere near where we were in the early 1990s. In 2000, we had a significant drop in fiber length, but we're staying fairly consistent with the 2001 crop.

“Another way to view the quality data is to look at the percentage of short staple in the crop. For 2001, we're running at about 25-percent short staple on average. In 2000, we were running about 90-percent short staple early in the ginning process,” he says.

In comparing Georgia's quality with that of other Southern states, Jost says the Florence, Birmingham and Memphis classing offices were showing better length than Georgia. Georgia also trailed the other states in uniformity, with a uniformity ratio of just under 81. Georgia's micronaire average was slightly better than Memphis and about the same as Florence and Birmingham.

In an attempt to get a better idea about the variations in quality across Georgia, Jost requested that the classing office separate the data by region, with reports from the southwestern, central, southeastern and eastern regions of the state.

“As we go across the state, from the southwest to the east, we see that our average length is decreasing fairly significantly. In the southwest and central part of the state, growers are averaging better than 34. But, as we come east, the average drops below 34.

“We also can look at this data in terms of short staple. In the southwest, we're seeing 13 to 15 percent short staple. But in the eastern region of Georgia, we're seeing more than 50 percent short staple. What's the problem? Is it weather or varieties?”

Looking at all possible weather parameters between regions, Jost concluded that rainfall was a primary factor affecting quality.

“As we go across the state, and short staple increases, rainfall decreases significantly. It definitely has an impact. The timing of the rainfall also was a factor. In the Statesboro area, we had a lot of rainfall up until July. Then, the rainfall stopped. In Camilla, located in southwest Georgia, good rainfall was received during the fiber development period.”

Rainfall or water from irrigation has a major impact on fiber length, says Jost. “We know that the elongation of the fiber is driven by internal water pressure. It takes water to make that fiber grow. The length is determined about three weeks after the pollination of the flower.

“Temperature also has an effect. Extremely low or high temperatures during that crucial fruit development period can affect length. But looking across the different regions of the state, we didn't see a lot of difference in temperatures.”

Plant nutrition is another factor that helps to determine fiber quality, says Jost. “Potassium is essential for maintaining internal cell pressure If potassium isn't available to the plant, or if it isn't being applied at the right time, it can affect fiber quality.”

Variety selection also affects fiber quality, he continues. “The variety sets the bar. Each variety has a maximum length that it can obtain. After that point, the environment can only shorten the fiber.”

The amount and timing of irrigation also can play a role in fiber quality, he says. “Some growers wait too long before applying irrigation water. They might wait until the cotton almost has wilted. By the time that pivot gets back around, the cotton at the other end could be severely stressed, and it could show up in fiber length.”

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