News Articles

GENERAL PRESS RELEASE January 1999

New technology report:

Important invention for agriculture makes debut.

New revolutionary aerial spray system promises to help farmers reduce pesticide use by as much as half.

First Aerial Version Of Electrostatic Spray System Now In Operation

While this agricultural aircraft is equipped with 50 pairs of electrostatic spray nozzles to apply one gallon of spray per acre, as few as five or six nozzles on either side of the boom can be used to make ultra-low volume applications of 12 to 16 ounces per acre.

An innovative new electrostatic aircraft spray system which uses an electrical charge to drive spray droplets to the target vegetation is expected to revolutionize agricultural aviation by improving spray deposition, reducing drift, and reducing total pesticide use compared to conventional spray systems.

The electrostatic system has been shown to significantly reduce spraying time, spray volume, and pesticide drift. The technology improves pest control by creating a uniform deposition pattern on target vegetation, even shaded leaf undersides and plant surfaces facing away from the spray direction.

The electrostatic spray system was developed by retired USDA-ARS agricultural engineer Dr. James B. Carlton, and patented by the USDA. Samples of the electrostatic nozzles were recently presented to members of Congress during budget hearings as an example of outstanding technology developed by the USDA’s Agricultural Research Service. The USDA has now issued an exclusive license to manufacture and market the technology to Spectrum Electrostatic Sprayers Inc., a leading manufacturer of electrostatic spray technology for orchards and field crops.

The first commercial version of the aerial system was installed in mid-summer, 1998 on an agricultural spray plane operated by a large international produce grower. Blake Dobbins, president of Spectrum Electrostatic, says the system has successfully met rigorous standards despite mechanical and electrical challenges posed by harsh environmental operating conditions.

Like Iron Fillings Drawn To A Magnet

Electrostatic spray charging technology is used to induce a charge of either positive or negative polarity onto the surface of nozzle spray plume droplets. The electric field generated by the charged drops drives or forces the spray toward any grounded object. When agricultural spray materials are so charged and released from an agricultural spray plane, deposition onto the foliage is enhanced, much like iron fillings are attracted to a magnet.

Field tests have yielded impressive evidence that electrostatic spray technology can reduce the total volume of material applied by air by as much as 90 percent, and pesticide use by up to 50 percent, while significantly improving pest control compared to conventional spray methods.

In 1995, Dr. Carlton and fellow USDA-ARS scientists I. W. Kirk and M. A. Latheef conducted studies to compare the performance of aerial electrostatic charged sprays with conventional aerial sprays for season-long control of sweet potato whitefly (SWF) on cotton. The study used a Cessna AgHusky alternately equipped with the electrostatic spray system, and a spray boom fitted with conventional spray nozzles.

The spray mixture was applied through the electrostatic spray system at a rate of 1 gallon per acre, and through the conventional spray system at a rate of 10 gallons per acre. Results of the study showed that electrostatically insecticides achieved equal or better control of SWF in cotton compared to conventional spray applications. Dr. Carlton reports that the electrostatic spray system can be used to apply nearly any liquid insecticide, fungicide, herbicide or fertilizer. However, the solution physical properties must be compatible with proper atomizing and charging from the nozzles’ electric field.

Engineered for agricultural aircraft, at the heart of this system is a futuristic-looking spray nozzle with a stainless steel cylindrical electrode encircling the nozzle tip to create a high voltage induced electric field on the spray shearing region. The non-electrically conductive nozzle tip produces a hollow cone plume of spray, while a brass body mounts the nozzle to the spray boom.

The spray system relies on two electric systems coupled to the aircraft battery to provide both positive and negative electrical charges. Dual voltmeters mounted inside the cockpit permit the pilot to monitor the electrical current, while dual rheostat controls allow the pilot to adjust positive and negative polarity charging voltage. The direct charging voltage, typically 8 to 10 kilovolts, is supplied to the electrode surrounding each nozzle tip by means of a small wire. The electrical ground connection to each nozzle is made through the aircraft frame.

Engineered for low volume and ultra-low volume applications of liquid insecticides, fungicides, herbicides and fertilizers, the electrostatic nozzles are designed to produce an extremely low flow rate. The number and configuration of the nozzles mounted on the spray boom vary depending on application rate, type of material applied, and aircraft speed. According to Dr. Carlton, 50 or more pairs of nozzles can produce an outflow of 1 gallon per acre, while as few as five or six nozzles on either side of the boom may be sufficient to make an ultra low volume application of 12 to 16 ounces per acre.

Benefits Of Electrostatic Spray Technology Proven In Ground Sprayers

Spectrum Electrostatic Sprayers Inc., based in Houston, Texas, has manufactured electrostatic ground spray systems for use in orchards, field crops and mosquito control programs for the past ten years. Blake Dobbins, company president, points out that the benefits of electrostatic technology are widely acknowledged by researchers and growers alike.

"Low volume electrostatic sprayers use from 50 to 80 percent less water than high-pressure sprayers, allowing operators to cover more acres per hour or day," he says. "The spray efficiency is improved, there’s less drift, and less spray solution dripping off the target vegetation".

That can add up to impressive savings, says Dobbins. University and private studies show that electrostatic sprayers consume up to 70 percent less fuel than high-volume sprayers to treat the same acreage. And because more of the spray solution reaches the target vegetation with less run-off, electrostatic sprayers can reduce total pesticide sprayed also means less risk to workers, and reduced impact on the environment.

"We expect the system to give aerial applicators an important competitive advantage", says Dobbins, whose company is now making preparations to support the boll weevil eradication program with aerial electrostatic spray equipment to apply ULV boll weevil insecticides, including technical malathion.

CALIFORNIA GROWER MAGAZINE

Vol. 20, No. 2 – February 1996

SPRAYING THE FIELD

New Sprayer Technologies Offer Growers a Wide Choice

by Michael J. Major

"Governments around the world are looking for up to a 50 percent reduction in pesticides, so the chemicals available to the farmer in the future will be less potent and will be active for only a short period of time", says Blake Dobbins, president of Southwest Electrostatic Sprayers in Houston, Texas. "There’s a long-range trend towards more efficient spray equipment to increase worker safety and reduce the amount of chemicals going into the environment."

While long-term changes may be inevitable, in the short term, they are just getting started. Although many of these changes appear promising, not all manufacturers currently see a reduction in chemical output as the wave of the future. For instance, David Lincoln at Air-O-Fan Products Corporation in Reedley says that his company’s new equipment is featuring power take off units with capacity for spraying larger volumes of air, thus covering a wider array of crops, thanks to the larger horsepower now being put into the tractors. "The idea of applying fewer chemicals to get the same job done is still in the proving stage," he says. "The so-called new ways of spraying are not proving to be satisfactory in terms of coverage."

Nevertheless, most innovators, both actual and projected, in orchard sprayer equipment aim to increase spray effectiveness through more efficient and innovative applications. The modifications range from low to high tech.

Low Volume Technologies Aim for Savings

Dan McGuire, southwest territory manager for AgTec, a division of AgChem Equipment Company, Inc. of Minnetonka, Minn., says that his company’s new equipment comes with a combination of the old and the new. The older, but still very relevant technology has to do with low volume spraying. "We learned years ago that low volume can save both water and chemicals," McGuire says. "You leave more on the tree and less on the ground or in the air."

Basically, AgTec’s unique metering system consists of two stainless steel plates with different-sized holes. Rather than having to change several nozzles and pressures, or watching for plugged holes, the AgTec product has larger holes encompassing a lower pressure. A squirrel cage band and high velocity air input breaks t he water particles into small droplets, instead of the big drops from a conventional sprayer.

Using the three factors of row spacing, vehicle speed, and rate per acre, and computing with a little slide rule that comes with the sprayer, the grower will easily know how to calibrate the meter. McGuire adds that his equipment has been able to put out low volume spraying from six to 500 gallons, and its newest large model now has a 600 gallon tank, all fiberglass.

Intelligent Machines Know Where to Spray

Durand-Wayland, Inc. of La Grange, Ga. offers a large line of sprayer options for fruit growers. Twin fan sprayers, oscillators, and a Streamliner sprayer are just some of the offerings. The SmartSpray 1000, actually a computer-based spray attachment, uses ultrasound technology to sense tree location and direct spray only onto trees, not in gaps, on the ground or in the air. Growers can adjust the output for different blocks or weather conditions using a hand-held terminal, which can be hooked up to a personal computer to generate reports of chemical usage and savings. SmartSpray is available as an add-on to new sprayers or as a retro-fit on existing sprayers. Durand-Wayland touts chemical savings of 25 percent with this option.

Ray Perry, director of sprayers for Durand-Wayland, maintains that machines like the SmartSpray represent a significant cost savings for the grower, as well as reduce chemical releases into the environment. "If a grower has a 400 acre orchard, a savings of 25 percent can be attractive over a year’s time," he notes. Yet Perry acknowledges that acceptance of such equipment has been slower than anticipated. "We expected that when we started making these machines three years ago, that acceptance would be in the 50 percent range among growers, but it’s closer to 25 percent." He attributes much of the resistance to the fact that this type of machine is computerized, and suspects there is some reluctance to put a high-tech machine into the hands of an untrained tractor driver.

Lightweight Sprayer-Vehicle is Nimble Option

Barry Jones, president of PBM Supply & Manufacturing, Inc. in Chico reports he is building a lighter weight vehicle, somewhere between ATV and tractor, which will use less fuel, minimize soil compaction, and get on the ground more quickly after rain. The vehicle has spray shields, and can either be put on cruise control with a set pressure and amount of spray, or use a computer-programmed procedure.

Air Blast Sprays Target Thorough Coverage

Rears Sprayers of Eugene, Oregon sells a variety of air blast sprayers mainly for orchards and the fruit industry, though it does manufacture some sprayers for row crops and specialty nurseries. In sprayer design, Rears president Mike Rear notes an "attempt to respond to the needs of the grower," and adds that changes in the availability of chemicals from one year to the next means growers’ needs often change.

One sprayer in the Rears line, the Powerblast Citrus Tower, relies on the efficiency of its design for evenness in coverage. Featuring a folding tower with a vertical row of spray nozzles along each side, the Citrus Tower releases spray evenly from the ground up, while an air-blast fan blows the spray inside the tree. Having nozzles close to the spray target ensures the whole tree is evenly covered, including the higher areas below the canopy.

John Hadaway, a managing director or Exel, Inc., distributors of Berthoud Sprayers in South Haven, Mich., says that one of the big advances he sees, from his perspective, are his company’s air boom or over row boom sprays. "These cannon type sprays shoot out 50 to 100 feet directly onto the product, with fewer passes and fewer chemicals, because the air gets down inside the plants," Hadaway says.

Though mostly used by vegetable growers, Berthoud’s air boom sprays are used by several California grape growers, because they spray the top as well as the bottom, giving superior coverage, Hadaway reports.

Scientific Solutions

High-tech solutions, such as electrostatic spraying, are accompanied with some controversy. Some feel the low-volume sprays don’t provide enough coverage to eradicate pests. Others insist that the precision available with electrostatic sprays make them the most economically and environmentally sound spray method available. Electrostatic spraying is not new , it’s been on the market for about 25-years , but environmental safety concerns with spraying are causing some to turn to this technology as an answer.

Southwest’s Dobbins acknowledges that electrostatic equipment currently has only a small market share, but maintains, "with increasing governmental regulations to reduce the amount of spray, farmers are going to have to change."

Dobbins contrasts Southwest’s technology with standard high-pressure equipment which uses a hydraulic high pressure nozzle and large volumes of water, making it, in essence, a hit and miss procedure. With electrostatic sprayers, droplet size is regulated by a patented air shear nozzle that breaks the liquid down into droplets, each of which is induced with a negative charge. All of the droplets repel each other, forming a larger pattern. Since the small charged particles hold a force 40 times stronger than gravity, they won’t fall to the ground, but are attracted to the positively charged leaves. Because the droplets repel each other, spray coverage is even, as drops adhere only to leaf areas otherwise uncovered by the spray.

According to Dobbins, the added benefit is the virtual elimination of drift, one of the main environmental concerns about spraying. "It’s pretty well acknowledged that electrostatic compared to common sprayers saves one third of the chemical and one third of the water costs, as well as two thirds of the time, since you don’t have to run back and forth to your water supply," says Dobbins. Added variations to this product include a boom sprayer with hydraulically-controlled wings that fold out, a back-pack sprayer useful for hilly areas which uses a leaf blower for manual applications, and a skid mount sprayer.

In 1996, Southwest Electrostatic Sprayers, Inc. changed its company name to Spectrum Electrostatic Sprayers, Inc.