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Corn+Soybean Digest

Beneficial Harvest Aids

Laudies Brantley has grown enough cotton to know when it's feasible to add inputs in order to boost profit potential. By using an effective harvest-aid defoliation program, all-important cotton quality is being protected. So is the bottom line.

Brantley and his son Dow operate Brantley Farming Co., a large-scale operation at England, AR, just southeast of Little Rock. Cotton is rotated with corn and soybeans. His 38-in. row cotton includes the latest in high-tech seed, including Roundup Ready, Roundup Ready Flex and Bollgard and Bollgard II stacked varieties. Furrow irrigation provides plenty of water if summer drought sets in.

Bill Robertson, University of Arkansas Extension cotton agronomist, says growers like the Brantleys count more on harvest-aid programs to get the most out of their crop after the bolls mature.

“The ultimate goal of a harvest-aid program is to protect the quality of the lint and seed and enable an earlier harvest,” says Robertson, noting that recent Arkansas studies looked at how harvest-aid timing affected the newer fine-fibered varieties.

Cotton quality concerns Brantley nearly as much as yield. Poor quality means price discounts. “The world is full of cotton,” he says. “The U.S. is seeing better yields and international production is up. It's important to produce quality cotton that is demanded by foreign and domestic mills and which will produce a better price for us.”

Being able to pick cotton earlier offers many advantages, as long as the crop is finished. It can help prevent trouble that may arise from a wet fall. Harvest schedules can be better managed for cotton, as well as corn and soybeans. “When the plant is fruited properly, there are several harvest-aid chemicals that can work for you,” says Brantley.

The Brantleys use a common harvest-aid program, but don't mind mixing in new products that have shown promise on their farm and others. A 95-ft. boom John Deere 4710 ground rig makes applications. It can cover 30 rows in one pass. If fields are too muddy, then aerial applications are required.

“Timeliness is essential,” says Brantley. “We start with a good clean defoliation that is normally achieved by applying Dropp (thidiazuron) or a generic defoliant at a rate of about 1 lb./10 acres.”

The second application is made about a week after the first application and includes 1/4 gal./acre of a defoliant, DEF or Aim, mixed with 1/3 gal. of Ethephon. “With that type of program we can usually see a complete kill,” says Brantley, adding that two applications were used in 2004. “Our goal is to have all of our cotton harvested by Oct. 31. We got 70% of our crop harvested before Oct. 8 in 2004, when a wet fall set in, the wettest fall we've seen since 1984,” he says.

There was also a successful harvest-aide program in 2005. “We were fully open in plenty of time,” says Brantley.

He credits the harvest-aid program for expediting the harvest and preventing a larger portion of the crop from being exposed to excessive rainfall in '04. But even with the rain, the Brantleys saw good yields. They experienced their highest yield ever, 1,675 lbs., from one field that received 14 in. of rain. Yields in 2005 were about 100 lbs. lower, but still good production from a smooth harvest period.

“Our harvest-aid program costs $20-25/acre for two applications,” says Brantley. “That's money well spent if it can help get the crop in early and sustain fiber quality.”

Robertson warns growers to be sure a crop has received an additional 850 heat units beyond cutout before starting the defoliation process. That's generally when bolls are 45-50% open and there are five nodes above the first cracked boll.

“Research in Arkansas indicates this approach will help optimize lint yield and loan values to achieve greater returns on early maturing varieties in situations where discounts associated with high micronaire values may occur,” says Robertson.

There are several new Roundup Ready-Bollgard stacked varieties that are producing excellent yields with improved fiber qualities. Robertson says there has been concern over whether the 850 heat unit level was sufficient enough for a successful defoliation program on these varieties.

“Our plots showed that DP 444BG/RR and Stoneville 5599BR performed well with harvest-aid applications at 850 heat units beyond cutout,” he says. “We looked at 750, 850, 950 and 1,050 heat units in our tests and the 850 level performed well. We look to get more data this year on these and other varieties.”

In his harvest-aid recommendations, Robertson says a once-over application can result in commercially acceptable defoliation and boll opening if applications are properly made. A once-over should involve an application of Finish or FirstPick tankmixed with DEF, Dropp or Aim, he says, adding that Dropp makes an excellent mix partner, when temperatures and regrowth potentials are high.

“As regrowth pressures subside, DEF provides an additional defoliation enhancement for either Finish or FirstPick,” he says. “Aim has proven to be an effective product for morningglory desiccation, as well as being a good mix partner with Finish or FirstPick. Remember to adjust rates to match conditions as the season progresses.”

For a two-application harvest-aid program, a second application containing Ethephon and DEF may be applied five to seven days after the first application removes enough leaf tissue to insure adequate coverage of the boll opener on remaining unopened bolls (good coverage is essential for adequate harvest-aid results).

“Rates will naturally be adjusted to reflect current weather and plant conditions and the urgency to achieve the level of boll opening needed to keep the pickers rolling,” he says. “Harvade may be substituted for DEF in the above program to achieve similar defoliation and enhance the weed desiccation.”

Robertson says the product Leafless, a combination of Harvade and Dropp, is also effective for weed desiccation with warm temperatures. “As temperatures decline, impacting regrowth potentials and plant activity, then products and rates should be modified to insure success,” he says.

For more information, visit the University of Arkansas Web site: Additional information is also available at the Texas A&M University Web site:

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