Pre-conditioning can make cotton defoliation easier
Feb 1, 2010 3:34 PM, By Roy Roberson, Farm Press Editorial Staff
A pre-conditioning defoliation treatment for rapidly growing, dense canopy cotton may pay off for growers, according to researchers at North Carolina State University.
As many growers in the Southeast found out recently, picking cotton in January is not a good idea. Thanks to a wicked and wet turn from Mother Nature, too many growers had no option but to pick into the New Year.
TIMELY cotton defoliation may prove easier when using a pre-conditioning treatment.
Recent results of tests on pre-conditioning treatments to prepare cotton for defoliation indicate there may be some advantages in timeliness and convenience that could have spared growers some of the stress of December and January picking.
The tests were conducted by North Carolina State University graduate student and researcher Seth Holt over two years in North Carolina and Virginia.
“It’s not unusual for cotton growers in any of the cotton producing areas of the country to have to defoliate cotton with rank growth and heavy canopy density twice. It is not only costly, but it is time consuming and can rob the grower of the opportunity to pick cotton when harvest conditions are good,” Holt told attendees at the recent Beltwide Cotton Conferences held in New Orleans.
“Often the cotton crop is uniform and ready for defoliation, but the grower can’t defoliate all his cotton because he can’t pick it fast enough to prevent regrowth and other harvest problems. If the grower is using a two or three-way combination defoliant, this can involve a significant number of acres and will get expensive real fast,” Holt explains.
By pre-conditioning cotton for defoliants, Holt explains his research team applied a low volume, cheap rate of a defoliant to prepare the crop for a full rate defoliation. Though he technically does defoliate twice, he contends the lower cost, slower acting early defoliation is cheaper and allows the grower a bigger window of opportunity to pick his crop.
In 2009, pre-conditioning could have allowed some growers to harvest more of their crop ahead of record-breaking December rains and snows and would have definitely paid big returns to the grower.
“Right now pre-conditioning cotton for defoliation is more of a convenience factor than anything else. Our tests in North Carolina and Virginia clearly indicate some differences between cotton that was pre-conditioned and then fully defoliated versus a one-time or two-time conventional defoliation. However, I must stress that so far we have not seen any definitive yield improvement (or decline) using this system,” Holt says.
Early fall pre-conditioning defoliation could promote rapid defoliation, remove older foliage for more complete defoliation, produce cleaner fiber and reduce weather-related harvest delays.
Holt’s research team looked at reduced rates of DEF, Dropp, Prep and ET. The standard defoliation was a three-way combination of DEF, Prep and Dropp. All were applied at 15 gallons per acre. The pre-conditioning treatments were applied seven days ahead of standard defoliation.
They used two aggressive, rapid growing, heavy canopied varieties for their tests — DPL 164 and Stoneville 6611. They applied six tons per acre of poultry litter on high moisture soils. “The idea was to create very rank growing plants and heavy canopies, which we did,” Holt says.
In both years a pre-condition rate of DEF worked well, produced a good level of defoliation and set the crop up well for standard defoliation. DEF, Prep and ET all worked comparably well in the second year of the test.
At all sites and in both years the heavily canopied cotton responded well to the pre-condition plus standard three-way defoliation program when evaluated seven days after the standard treatment and 14 days after the pre-conditioning treatment.
Compared to a one-time standard three-way defoliation all the pre-condition, plus standard defoliation treatments produced a higher percentage defoliation than the standard three-way treatment alone.
Regrowth was not statistically different 21 days after the one-time standard treatment and 28 days after the pre-conditioning, plus the standard treatment.
“Visually, you could clearly see both years at all locations that the pre-conditioning treatment, plus the standard treatment, produced a higher level of defoliation. In the standard treatment you could consistently see more leaves in this thick, dense canopy,” Holt says.
It seems clear that a pre-conditioning program plus a standard defoliation application will be a better strategy for thick canopies by allowing more efficient defoliation. In some cases, the pre-conditioning strategy improves overall defoliation, perhaps produces early harvest and allows the grower to maintain the time window between standard defoliation and harvest — not prolonging the period.
“I want to make it clear that the pre-conditioning treatment in our tests did not improve yield, lint percentage, fiber quality or bolls above cracked bolls in any of the treatments,” Holt concludes.
“We will look at the economic benefits of using one of these pre-conditioning treatments. We will look at different application methods and other factors in addition to determine whether this can be a consistent money-making or cost-saving strategy for growers,” the North Carolina State researcher concludes.
email: rroberson@farmpress.com
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