Reducing Spray Stray

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Kawak Aviation Hydraulic SystemSpray drift. Two simple words, but when combined, they become a double-edged sword that slices into your dealership’s profits and reputation in one stroke.

The pain of the costly waste of fertilizer/crop protection products for you and your grower-customer is only surpassed by the damage of the ensuing stewardship and environmental nightmare. No one — not the custom applicator, the dealership, the grower-customer, the neighboring grower/
homeowners, nor the general public — is unaffected by spray drift.

For those reasons, manufacturers continually address the issue, bringing new and revised products to the marketplace for custom applicators and growers. Here are some of this year’s products.

Adjuvant Adjustments

Adjuvants are a key component of the fight against spray drift. “U.S. applicators have taken full advantage of using adjuvants for their drift retardant qualities,” says Bryan Young, Southern Illinois University weed scientist and author of the bi-annual “Compendium of Herbicide Adjuvants.”

Newer drift reduction adjuvants include nontraditional products, he says, such as Agriliance’s crop-based Interloc, derived from vegetable oil, and UAP/Loveland’s Valid, a soy lecithin-based product. As part of that trend, Agriliance brought Pow­erLock — a premix of Interlock and Preference, a premium soy-based nonionic surfactant — to the marketplace just last season.

Brand new products include Garrco Products, Inc.’s Control, a lower-cost deposition aid that mixes easily with water and won’t plug the application system. John Garr II, Garrco president, notes that Control was the top performer in several university studies on adjuvants “at significantly less cost. It costs between 5 cents and 10 cents per acre to use.”

The product can be used at 1, 2, or 3 ounces per gallon; the rates differ for ground and aerial applications. Garrco offers Control WM for use with Monsanto’s Roundup WeatherMAX or Roundup Original MAX when ammonium sulfate is not included in the tank mix.

Garrco, located in Converse, IN, markets its proprietary products directly to dealerships. “Dealers can market Control to get their margin while giving the grower-customer a good value,” says Garr.

High-Speed Hydraulics

Because of accelerated speeds, aerial applicators must be able to quickly control product flow, a need that hydraulic dispersal systems — adapted from the helicopter industry — are answering.

Huoma Avionics of Huoma, LA, offers its Auto Cal Flow controllers, which can be used with either liquid or dry products at both constant and variable rates and can be used with Satloc, AgNav, and Del Norte GPS systems. This year’s models are a half-second faster than last year’s, according to Huoma’s Jim Graves.

While the prescription model uses automatic on/off to control product flow, the manual version has an override for turning the spray off. “When the plane goes over a hill at 120 to 200 feet per second and there’s a school bus full of kids, that pilot needs final control,” Graves says.

The ability to combine a hydraulic system with precision application tools provides a number of benefits for aerial application, including product and fuel savings. “It even turns the boom valve off and on, and allows the pilot to concentrate on flying the airplane,” says Peter Warbington, sales manager for Kawak Aviation Technologies, Inc., Bend, OR. “It’s the future of this business. Any time you do a better job without drift, it helps the environment and community.”

Kawak’s system was originally developed for the U.S. State Department to use on Air Tractor 802s. The fan in front of the aircraft was removed to install the hydraulic system, reducing turbulence and creating an even spray swath. “It also takes 69 less horsepower to push the plane through the air because the fan creates drag, requiring more horsepower,” he adds. “Removing the fan reduces fuel consumption, too.”

Kawath is currently working with Satloc and Del Norte on a GPS-controlled gate for dry materials such as fertilizer that would also make upwind and downwind adjustments for even application. Certification could come by the end of the summer.

Graves knows of one company that’s currently testing an injection controller for airplanes, says Graves. The controller would allow an applicator to spray two products at the same time — one at a constant rate, the other at a variable-rate.

New Nozzles

Nozzles are an integral part of controlling spray drift, and this year’s class includes new and updated models.

Hypro LLC is offering a revised version of its Guardian liquid nozzle. “We’ve simplified the design to provide trouble-free flow through the tip, minimizing plugging concerns for more on-target insecticide and fungicide applications,” says Mark Mohr, sales engineer.

New studies have found that slightly larger droplet sizes, rather than the traditional smaller droplets, provide more effective canopy coverage when dealing with Asian soybean rust, aph­ids, and other newer pest concerns. For that reason, Hypro intentionally built in a 20-degree incline to fine-tune application. The nozzle can be reversed for spraying grass weeds. The FastCap Complete design includes snap-in strainers for easier installation, change-out, and cleaning.

This year’s new models include the VariTarget, distributed by GP De­la­van, and TeeJet’s TTI (Turbo TeeJet Induction) and AIXR.

According GP Delavan, one feature-rich VariTarget equals eight conventional drift reduction nozzles. The features include on-the-go flow rate control, uniform spray coverage, optimum droplet size, and fast rate change response. It can be used with manual or automatic rate controllers and adapts to conventional nozzle bodies and spray systems.

TeeJet’s TTI all-plastic, compact nozzles offer air induction technology, which produces extremely coarse droplets for ultimate drift control. The Turbo TeeJet technology provides excellent wear resistance and pattern uniformity.

The compact, two-piece AIXR utilizes air induction technology to produce a droplet that’s smaller than one from  conventional air induction but larger than one the standard Turbo TeeJet nozzle creates. This in-between size promotes a perfect balance between plant surface coverage and drift control, according to TeeJet’s Marty Heyen. The special polymer material is chemical resistant and can be used with acids.

Ratings To Help Decisions

Agricultural product spray drift has been a major focus on the U.S. regulatory front, too. Several years ago, EPA created the Drift Reduction Technology Project, a voluntary program to provide private and commercial custom applicators and growers with the information needed to make more informed spray technology decisions.

“Spray drift is a significant concern for applicators and nearby residential areas,” says EPA’s Jay Ellenberger, the project’s policy leader. “State government agencies are charged with enforcement, and they spend significant resources dealing with drift complaints.”

Recognizing the lack of quantifiable information about product drift reduction effectiveness as a major barrier for applicators, EPA brought together national and international spray drift experts from across the ag spectrum to discuss solutions. The group identified two key challenges: the need for an established U.S. program to verify drift reduction technology performance, and a mechanism to encourage applicators’ use of these drift reduction technologies.

Implementation Begins

The project recently completed its first major milestone, drafting a test method that independent researchers can use to measure the potential of a technology to reduce spray drift.

Actual testing will begin this summer, beginning with spray nozzles and drift retardant chemicals. “We plan to start off fairly simply,” Ellenberger says. “We’ll solicit companies to voluntarily test their spray nozzles or drift retardant chemicals in wind tunnels. EPA will probably pay for the first round of testing.” The tests will replicate aerial and ground row/field crop application situations.

All tested spray technologies — not just nozzles and drift retardant — will earn a specific performance rating, which manufacturers can choose to promote. And ag chemical manufacturers may also elect to update their product labels to include use recommendations with spray drift reduction-rated equipment. After an EPA assessment, those labels may have fewer restrictions for applications with verified technologies.

This information will help applicators select and use spray technologies that have been proven or verified to significantly reduce spray drift. “Once a custom applicator decides which ag chemical to use, they can then purchase and use equipment that has been verified to reduce spray drift,” Ellenberger says.

EPA expects the first-round testing results to be analyzed and reviewed this fall. “We hope that by early 2008, pesticide manufacturers will put ratings recommendations on new product labels and when they amend a product label,” Ellenberger says. “The label revisions can be registrant- or EPA-initiated.”

The EPA project has raised concerns in some industry quarters about reinventing the wheel, especially the nozzle manufacturing sector. Many of these companies have already spent time and money on testing to meet the American Society of Agricultural and Biological Engineers (ASABE) Standard (S-572), which classifies noz­zles based on droplet size compared to an established nozzle set, according to Dr. Bob Wolf, Extension specialist, application technology at Kansas State University. Currently, spray nozzles are classified by this standard into the following droplet size categories: very fine, fine, medium, coarse, very coarse, and extra coarse. Before introducing a new nozzle into the marketplace, it needs to be tested.

Droplet Focus

The focus on droplet size characteristics is centered on the concern to reduce drift while still maintaining crop protection product efficacy for the targeted pest. “Selecting the spray nozzle to deliver the appropriate droplet size is becoming more critical today,” says Wolf.

“For most agricultural applications, nozzles producing medium- and coarse-sized droplets would be selected,” he says. “Contact-type herbicides may be best with medium and systemic-type herbicides may work well with the coarse-sized droplets. For applying fungicides for Asian soybean rust control, and for insecticides, a smaller droplet size (medium) may be better. From a drift perspective, fine and very fine droplet sizes should be avoided.”

Testing a new nozzle for the ASABE standard can be accomplished by sending the nozzle to the original test lab at the University of Tennessee, or the standard nozzle test set can be sent to the manufacturer for testing in its own test lab. Manufacturers are including this information in their marketing literature.

The ASABE standard enables applicators to see what droplet size a particular nozzle type will produce at a given orifice size and pressure. This allows the applicator to factor in the droplet size when calibrating the sprayer for application volume. In fact, Wolf notes, product labels are starting to specify a particular droplet size for use with the product, which applicators are then required to match.

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