Growers switching from early-maturing cotton varieties to later-maturing varieties need to remember that more intensive management is required, says Bill Meredith.
There has been a significant switch in variety types in recent years, he said at the joint meeting of the Delta Council's Ginning and Cotton Quality Improvement Committee and the Southern Cotton Ginners Association at Stoneville, Miss.
“In 2003, six varieties, all early-maturing cottons, made up the biggest portion of the Mississippi crop. Only about 22 percent were mid-maturity or late maturing. But this year, 65 percent of the varieties are in the later, mid-maturity group.”
Meredith, cotton geneticist with USDA's Agricultural Research Service at Stoneville, Miss., says these varieties “generally grow taller and have more leaf, and you have fewer days to harvest them.
“They are more vulnerable to late-season weather adversities and insects. With more biomass leaf material, it will probably be more difficult to defoliate the crop and more care may be required in ginning. Overall, there isn't as much flexibility with these later-maturing cottons.”
On the plus side, he notes, “These varieties can produce bumper crops — they have the capability to give growers the big yields they want.
“They also tend to have better staple length and micronaire than most early-maturing varieties.
“And this year, in our area at least, they may have escaped problems from the heavy rains. We've had gaps in the fruiting patterns of our early-maturing varieties, but the later varieties that just started fruiting the last of July may not suffer. A lot will depend on weather for the next month and the harvest season.”
The number of days available to produce a crop is important with later-maturing varieties, Meredith points out.
He cites one study, comparing Deltapine 555 against Deltapine 444, in about 13 tests planted early, he says 555 out-yielded 444 by 352 pounds on average.
“It's highly significant that 555 took advantage of a long, full season, and made a tremendous yield, which caught people's attention. But when the two varieties were planted a bit later, around May 10, yields were about the same. When they were planted around May 20, the early variety out-yielded the other by about 320 pounds per acre.”
What's important in determining the success of a new variety? “Whether the grower had a good year with it,” Meredith says.
“That's why everyone switched so heavily into later-maturing cottons this year. They had a bumper crop in 2003 and this year everyone was switching to Deltapine 555 and Stoneville 5599. Conversely, when there's a bad year, variety is blamed for that, too.
“What happens this year has a lot to do with what growers plant next year.”
With the current concern in the international market about the fiber quality of U.S. cotton, Meredith says, “variety can have an impact on many of these problems; fiber quality has a strong genetic input.”
Breeding programs don't change very fast, he says — “not as fast as the world is changing now.”
“Historically, yield hasn't been going up very fast in the last 20 years, only about 3.5 pounds of lint per acre from all our technologies combined: breeding, harvesting, growth regulators, the entire package. There have been tremendous yield shifts from one year to another, and that's very troublesome — why we can have variations of several hundred pounds.
“Ten years ago, we had an average staple of about 35-1/2 in Mississippi; now it's about 34-1/2. We've let it slide, mainly because there wasn't much demand for another 32nd of an inch, or any financial incentive. Now, with two-thirds of the market overseas, they're wanting it at least a 32nd of an inch longer.
“Many of us don't like change and the aggravations it can bring,” Meredith says, “but to be able to survive, you've got to be flexible.”
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