Hot air for pest control
A new machine is designed to kill insects and fungi with a quick blast of hot air.
Chilean fruit grower Florencio Lazo has invented a machine that he thinks could eliminate the need for pesticide or fungicide sprays in an orchard or vineyard. His Thermal Pest Control (TPC) machine shoots a quick blast of hot air at the trees or vines as it's driven through the orchard or vineyard, killing fungi and insects and boosting the plant's own defense system, he says.
Lazo has 100 hectares (240 acres) of fruits, including grapes and cherries, in Rosario, Chile, and says when he uses the heat treatment he doesn't need to spray them at all. In addition, the heat shock appears to improve the color, flavor, and storage capability of his cherries.
Lazo said the idea behind the invention came to him just by chance, "like most big discoveries in history." His farm is in a frost-prone area. As a pilot, he was familiar with aerodynamics. During the mid-1990s, he developed a machine with a liquid petroleum gas (LPG) burner that blew streams of 100°C (212°F) air into the vineyard to create a thermal barrier to protect it from frost.
He patented the machine in the United States and Chile, and, according to the World Intellectual Property Organization's Web site, the invention earned Lazo a national prize for innovation. He sold about a thousand machines worldwide.
One night, when he had used the frost machine all night long in his own vineyard, an employee expressed concern that the heat might be killing the buds on the vines. In fact, the leaves were not damaged, and Lazo recognized the potential beneficial effects of a heat treatment. He set to work to develop a similar machine that used heat to control pests and diseases.
His Thermal Pest Control machine is fueled by propane and sends out blasts of 100°C air at a speed of 220 kilometers (136 miles) per hour in a special laminar flow. The machine is about 2.5 meters (8 feet 3 inches) long and 1.5 meters (5 feet) wide and weighs only about 100 kilos (220 pounds).
Though the machine burns propane, Lazo said research at North Carolina State University shows that carbon-dioxide emissions from the propane are lower than the emissions from farm chemicals.
The machine is pulled through the orchard or vineyard by a tractor at about 4 to 5 kilometers per hour (2.5 to 3 mph), exposing each tree or vine to heat for a fraction of a second. In grapes, Lazo applies the heat shock every 15 days from bloom to veraison and every week from veraison to harvest. He says treated grapes have better color and thicker skin. "We've seen this consistently," he said.
Heat-treated cherries have better color and store better, he said, and growing costs are reduced significantly by not having to apply chemicals. He applies nothing but a winter copper spray. Lazo cites research at the Institute for Agricultural Research and Caltholic University in Chile showing that the heat treatment controls Botrytis and sour rot in table grapes better than fungicides do.
Lazo initially sent one machine to New Zealand for testing, with successful results. "Sometimes, things we're seeing in Chile, we think this is unbelievable, this is still by chance or just special conditions, but the same things were happening 10,000 kilometers on the other side of the Pacific Ocean," he said.
He then applied for patents in the United States and other regions around the world, including Europe, Chile, South Africa, New Zealand, Canada, Mexico, and Argentina, and in 2007, his company, Lazo TPC Global, Inc., introduced the new technology. He now has 37 machines in Chile, more than 20 in California, and several in Europe, he reported.
His partner, Marty Fischer, who is president of Lazo TPC Global and is based in California, said the machines are leased rather than sold, so that the company can control the technology while allowing growers to try it out.
Fischer said research is being conducted this year at Fresno State University to assess the machine's ability to control pests and diseases, but results won't be available until later this year. "We're in the test and experiment phase of this technology," he said.
Lazo believes that one of the greatest potential benefits is the opportunity to differentiate the product in the marketplace. Fruits are a commodity, but fruit grown with the Thermal Pest Control system can be certified chemical-free.
Growers who lease the equipment are licensed to market their fruit under an umbrella consumer marketing program and use the slogan "WOW, I'm Certified Grown Without Pesticides." A small amount of fruit produced in Chile will be certified by PrimusLabs and test marketed under the WOW logo this year, Fischer said.
To qualify for certification, growers must apply no insecticides, fungicides, or herbicides while fruit is on the tree, although organic or conventional pesticides can be applied during dormancy or after the produce has been harvested. The Thermal Pest Control certification does not cover postharvest practices.
Kyle Mathison, who grows cherries in Washington State, California, and Chile, said he saw the results of the treatment in Chile, and it appeared to be effective. He said the trees seemed to be healthy, though the heat treatment made the leaves appear leathery. He was told that treated grapes matured five to ten days earlier and said he was leasing a machine for a cherry orchard in Bakersfield with the hope of having cherries on the market earlier. He also thought it would be a tool to control black cherry aphid.
"We just have to see if it works," he said, "But I talked to people in Chile who use it on table grapes, and it seemed like it was one of those things I thought I should try."
Fischer stressed that production using Thermal Pest Control is different from organic production. To be certified under Lazo TPC protocols, no chemicals may be applied between bloom and harvest, but in organic agriculture, nonsynthetic pesticides may be used. He said Lazo TPC is not promoting the heat treatment as an organic practice, as all organic practices must be approved by the organic programs.
A Thermal Pest Control method could help reduce insecticide and fungicide use, and have a positive effect on the environment and public health, says Dr. David Pimentel, entomologist at Cornell University, New York. However, more research is needed on all aspects of Thermal Pest Control to better understand how pests are controlled as well as the physiological changes taking place in the plant when treated with high temperatures for a brief period of time, he said.
It is possible that chemical changes that occur in the plants following treatment activates the natural plant defense system, he said. This possibility is being investigated at Fresno State University.
Previous research has shown that some insects and fungal organisms can be killed by a ten-second exposure to a temperature of 60°C (140°F). Soft-bodied insects such as aphids would be particularly susceptible, he believes, but more data is needed on the length of exposure required to kill a wide array of insects and fungi. If they were protected by limbs or leaves or were in the stem bowls of fruit, where they were less exposed to the heat, they might survive longer, he said.
For more information, check the Web site, www.lazotpcglobal.com.