Some use ground applications: Time, weather alter defoliation plans

The curve balls keep coming, with each one more unparalleled and startling than the one before. Record amounts of untimely late-season precipitation, extended periods of near-100 percent humidity and the day-by-day uncertainty of whether or not aerial applicators can take to the skies due to concerns raised by the tragic events of Sept. 11 have all left their mark on the 2001 cotton crop.

At presstime, the planes were back up in the air over Delta cotton fields, but as one Mississippi aerial applicator put it, “We're getting approval to fly on a day-to-day basis.”

“The fact that the planes are up one minute and down the next is definitely delaying cotton defoliation. There's no doubt about it,” says Louisiana cotton specialist John Barnett.

Barnett says that some of his state's cotton growers are moving to ground equipment for defoliation applications, but for many the switch means risking damage to the cotton plants.

Charles Ed Snipes, Extension cotton specialist at Delta Research and Extension Center in Stoneville, Miss., says, “Anything you were planning to put out by air can certainly be put out by ground. You just need to plan ahead and go back to the basics of good coverage.

“Defoliants can be applied by air with high-clearance application equipment, it just takes a lot longer and you've got to plan to start early and end late,” he says. “Ground application is still a very viable option, it's just that most people aren't set up to cover large acreages of cotton by ground.”

Whether cotton growers are applying defoliation products by ground or by air, Barnett says the bigger problem right now is controlling the plant re-growth caused by the adverse weather conditions in late August and early September.

Currently he is recommending applications of Dropp, Leafless, Freefall or Ginstar. “Those four are the strongest-performing defoliants against re-growth,” Barnett says. “In some areas, we are also recommending an application of Prep or a Prep compound to open bolls and allow growers to get in the field and harvest as quickly as possible.”

For those growers considering the harvest of severely damaged cotton, Barnett recommends an application of Def or Aim. “If you've got a large amount of boll rot, hard lock or germinating, sprouting cottonseed, then you need to go the cheapest way possible.

“In these types of situations, if you are going to defoliate, you need to spend the least amount of money you can get by with because the value of those cotton fields has been greatly decreased.”

Arkansas cotton specialist Bill Robertson says he hasn't seen either the re-growth problems or the severely damaged cotton, to the extent they have been reported in Mississippi and Louisiana. “We were just about ready to start putting a lot of our defoliants out when the adverse weather came along, so we avoided many of the problems that hit Louisiana and Mississippi growers,” he says.

“We've pretty much got out of the boll rot climbing up on the plant, but we did see a lot of boll rot earlier, on cotton acreage south of the Arkansas River. Boll rot cost many Delta growers at least a couple of hundred pounds of yield per acre,” he says.

“A farmer I visited a few weeks ago had an early yield potential of 1,200 pounds per acre, but he's lost two-thirds of the stocks due to boll rot and hard lock.”

Robertson says his general defoliation product recommendations are Def, Dropp, and Prep. Growers can also substitute the Def application with Aim, at a rate of two-thirds ounce per acre.

“Our standard recommendation for irrigated cotton is a two-shot treatment beginning with a tankmix of Dropp at one-tenth pound per acre, Def at one-half pint per acre, and Finish at 4 ounces per acre,” he says. “Then, we follow that up with a boll opening rate of Prep, possibly mixed with two-thirds pint of Def per acre to clean up any remaining leaves.”

The application rate of Prep, he says, depends on the temperature and how fast a grower needs to get a picker in the field. “With cooler temperatures, a quart of Prep per acre would be the least amount I would use. If you are getting in a bind with the airplanes up and down again, and you're fairly close with the picker, then you need to go the top end of the Prep rate, and apply two and two-thirds pints per acre. Even that treatment, though, isn't going to open up the bolls quite as quickly as growers would like due to the lower temperatures making it take a little longer,” Robertson says.

For dryland cotton, he says, there are almost as many defoliation mixes and combinations as there are producers. Two of the most common dryland tankmixes Robertson recommends are Finish and Dropp, or CottonQuik and Dropp.

To control weed pressure, Robertson suggests including Harvade with your defoliation tankmix.

“For the most part, all of the defoliants have worked very well this year,” he says. “In some of our early dryland cotton plots near West Memphis, Ark., we tried to stretch rates out in order to cut costs and, even then, everything worked well. The only disadvantage we documented was some re-growth after 10 days or so, but that was with very low product rates.”

Just as important as the delays in cotton defoliation, Barnett says, is the damage the flight stoppages are doing to the boll weevil eradication program. “This is a critical time for the eradication program's fall diapause program and if we miss too many insecticide applications, we're going to see some weevils go into overwintering.”

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