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Cotton variety evaluations available to producers

Each year cotton producers make difficult decisions about what varieties to plant. “These decisions are difficult because producers have so many options that change every year,” says Randy Boman, agronomist with Texas Cooperative Extension in Lubbock, Texas.

But help is available from data collected from large-scale tests conducted by Boman; smaller-plot tests conducted by John Gannaway, cotton breeder at the Texas Agricultural Experiment Station at Lubbock; and Verticillium wilt tests conducted by Terry Wheeler, research plant pathologist at Lubbock. The three work cooperatively to maximize the impact of their research.

“We begin testing procedures by examining current and historical test results,” Boman says. “And based upon these results and the availability of newly-released varieties, we decide which ones to include in our respective test programs.”

Extension carries out two types of tests on producers' farms. Boman and team conduct the more detailed, large-scale tests at three locations. The producers choose the varieties to be tested. These will include 10 or more picker and stripper varieties that represent a range in maturity and fiber properties. Some varieties have transgenic characteristics such as herbicide and insect resistance, and stacked genes.

Cooperating producers plant each variety in three approximately, one-acre plots and farm them in their respective herbicide technology systems. In the fall, with Extension supervision, producers strip harvest individual variety plots, dump the bur cotton into a weighing boll buggy, then into a module. They dump all three plots of each variety into the same module, gin it, and send lint samples to the USDA-AMS classing office.

“Subsequently, we report for each variety: commercial turnout percent; bur cotton yield, lint yield, seed yield, and seed weight in pounds per bale; lint loan value in dollars per pound, gross loan value, seed value, USDA-AMS classing results, cultural practices used and the net per-acre value,” Boman says.

Extension also reports costs for ginning, planting seed, technology and other system specific items; and costs of plant-growth regulators, insect and weed control chemicals, harvest-aid chemicals; and costs for applications.

Boman also oversees several other replicated tests on the High Plains with cooperative Extension agents and producers. “We conduct tests in essentially the same way we do the three large-scale, detailed tests. However, instead of having the cotton ginned at a commercial gin, grab-samples are taken from each plot, ginned at the Texas A&M University Research and Extension Center at Lubbock, and the International Textile Center at Texas Tech University, makes fiber samples analyses.”

Data from these tests are essentially the same as those from the three large-scale tests.

Gannaway conducts variety tests, late-planted variety tests, new varieties and strains tests, Roundup Ready Flex tests, a regional high quality test, a bacterial blight resistance test, a Verticillium wilt resistance test, and a nematode strains test — all grown under irrigation. Wheeler makes the bacterial blight, Verticillium wilt and root-knot nematode ratings.

Gannaway also conducts several dryland variety and Roundup Ready Flex tests.

Sites for the various dryland and irrigated tests include Halfway, Lubbock, Lamesa, Pecos and Tulia.

“From all these tests we determine lint yield, lint loan value, gross loan value, percent turnout and percent lint. We also ascertain micronaire, the length, uniformity, strength, and elongation of the lint; and leaf index and color grades. We measure boll size, seed index, lint index and seed per boll,” Gannaway says. He also reports varietal ratings for storm resistance and earliness.

“When we accumulate three years or more of data for a group of varieties we calculate comparable lint-yield averages. These averages enable producers to make more realistic yield comparisons among the varieties in a given group,” Gannaway says.

Wheeler tests varieties for resistance to Verticillium wilt at several producer locations that have a history of wilt problems.

“We normally determine the percentage of wilt-infected plants in August. We harvest the plots and determine for each variety the lint yield,” Wheeler says.

Wheeler also calculates an index number for each variety, which takes into account the variety's relative wilt ranking and relative lint yield (compared to the most wilt susceptible and highest yielding variety in each test). “Producers who have fields heavily infested with Verticillium wilt should use the index extensively in making variety selections,” Wheeler says.

“We test varieties from all the seed companies and include varieties having all the various transgenic traits. We also test conventional varieties, and both stripper and picker types. The complete list of tested varieties will be available on the Extension's Web site by January 2007.”

Results from these and other tests conducted by Boman, Gannaway and Wheeler are made available in media news releases, on the Web site, at Texas Cooperative Extension offices and at Texas A&M University System Agricultural Research and Extension Center at Lubbock.

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