Cotton harvest-aid guide available

Writer: Joe Bryant (806) 746-6101 E-mail: j-bryant1@tamu.edu
Contact: Dr. Randy Boman (806) 746-6101 E-mail: r-boman@tamu.edu

LUBBOCK–In the race against the clock to harvest the maturing High Plains cotton crop, harvest-aid chemicals can play an important role, says a cotton agronomist with the Texas Agricultural Extension Service.

“Weathering losses in the High Plains can result in considerable reduction in the dollar value of the crop unless measures are taken to protect yield and quality potential,” said Dr. Randy Boman, Extension Service cotton specialist. With some three million acres around Lubbock planted to the crop, that potential for loss is significant, he said.

“Harvest-aid chemicals are generally applied to hasten the harvest of a mature crop and to reduce those potential preharvest losses of lint yield and fiber quality,” Boman said. “Proper use will result in earlier harvest, preservation of fiber quality and fewer seed quality reductions due to field exposure.”

But what works best one season isn’t necessarily the best for the next season, he cautioned.

“Several factors affect the performance of harvest-aid chemicals.”

To help growers decide what, when and how to best take advantage of available chemicals, Boman and Dr. Wayne Keeling, systems agronomist with the Texas Agricultural Experiment Station here, have prepared a six-page publication, “1997 High Plains Cotton Harvest-Aid Guide.” It is available at county offices of the Extension Service across the South Plains, or on the Internet at http://lubbock.tamu.edu/html/html/taex/focus/focus.html

Boman and Keeling listed six factors which increase the performance of harvest-aid chemicals

* Warm, calm, sunny weather;

* Soil moisture relatively low, but sufficient to maintain the cotton plant in active growth without moisture stress;

* Relatively low soil nitrogen levels;

* Leaves active and uniformly expanded on plants;

* Little or no secondary growth on plants;

* Plants with a high percentage of open bolls that have reached “cutout” and shed some mature leaves.

Conversely, they said, some of the factors which negatively affect harvest-aid chemical performance are:

* Applications made under cloudy conditions with temperatures below 60 degrees;

* Prolonged periods of wet weather following treatment;

* Plants in vegetative growth with low fruit set;

* Plants severely moisture-stressed with tough, leathery leaves at time of treatment;

* High soil moisture and nitrogen levels which contribute to rank dense foliage and delayed maturity;

* Plants exhibiting secondary growth (regrowth) following a “cutout” period;

* Improper calibration of application rates and poor spray coverage.

The harvest-aid guide provides suggestions on determining crop maturity and discusses the three basic categories of such chemicals: desiccants, which cause the plant to dry down; defoliants, which cause leaves to drop from the stems, and boll openers. It also covers points to consider in selecting and applying the chemicals, harvesting the fields and preventing lint contamination, and contains a table to help in the decisions.

“Crop maturity determination is critical for a successful harvest-aid program,” Boman said. “Harvest-aid chemicals can’t increase the rate of fiber development. Only additional good growing weather, including open skies and adequate heat units combined with functional leaves, can mature cotton bolls.”

-30-