Researchers Discover Dramatic Insect Control with Innovative Thermal Cotton Defoliation Technology


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Washington, D.C. (January 12, 2006) – USDA-Agricultural Research Service (ARS) and New Mexico

State University researchers have demonstrated through recent field trials that propane-powered thermal defoliation can significantly reduce insect populations that are responsible for the occurrence of sticky cotton.  Dr. Paul Funk and Dr. C. Scott Bundy shared the results of these trials at the 2006 Beltwide Cotton Conference, held January 3-6 in San Antonio, TX.

Thermal defoliation research revealed a dramatic decrease in populations of the silverleaf whitefly and

cotton aphid.  This empowers cotton growers in the battle against insect pests that produce honeydew, which results in sticky cotton. Sticky cotton has been a concern of growers in the southwestern U.S. for more than 15 years, because when left untreated, it can stop processing in cotton ginning facilities.

The study, which was conducted in California, New Mexico, and Texas, demonstrated that the use of propane heat for defoliation also provided results faster and gave growers greater control over harvest timing.  Research shows that there are a host of advantages to propane-powered thermal defoliation; notably, the crop can be harvested just a day or two after treatment, compared to up to 14 days for chemical defoliation.

The U.S. propane industry, through investments made by the Propane Education & Research Council (PERC), has partnered with USDA-ARS to conduct field trials to determine if using propane-powered thermal defoliation could serve as an effective alternative to harvest-aid chemicals.

A two-row prototype of the defoliator was tested last year, and a larger unit will be tested in 2006 as the technology is scaled up for commercial production.  “By using a larger machine in this year’s testing, we hope to learn more about the economics of thermal defoliation,” said Mark Leitman, PERC’s director of agriculture programs.

The thermal defoliation technology propels a stream of moving air heated at 380 degrees Fahrenheit (193 degrees Celsius) through the cotton canopy. The air efficiently transfers heat to kill the leaves while preserving the cotton. The thermal defoliator design also includes a return air path that increases air penetration while reducing fuel consumption.

“Propane-powered thermal defoliation holds great potential for organic producers for a more timely harvest, greater efficiency and reduced fiber quality degradation,” said Funk, an agricultural engineer with USDA-ARS Southwest Cotton Ginning Research Laboratory in Mesilla Park, NM. “In addition, this type of defoliation is not dependent on favorable weather conditions as are traditional harvest-aid chemicals, and this is an attractive advantage for all growers.”

The use of propane fuel to create defoliating heat also has numerous environmental benefits over chemicals. The heat will not contaminate the soil or groundwater, and propane combustion emissions during defoliation are inherently low in air pollutants listed under the federal Clean Air Act.

Through grants from the U.S. Environmental Protection Agency, additional research to evaluate the effectiveness of thermal defoliation will be conducted this year by researchers at the University of California-Davis and the Alternative Fuels Research and Education Division of the Railroad Commission of Texas.  Field trials will be conducted during the 2006 harvest season in Texas’ Lower Rio Grande Valley and at the University of California Field Research Station in Shafter, CA.

PERC’s vision in agriculture is that by 2010, the agricultural industry will recognize propane as a preferred energy source offering exceptional value. This value is achieved through a unique combination of product benefits, including cost-effectiveness, efficiency and productivity, portability and environmental friendliness.

For more information on PERC and its programs to promote the safe and efficient use of propane in agriculture, call (202) 452-8975 or visit or and click on the “Trades” link.