Tunnel sprayer helps reduce drift in orchards

06/20/2011 04:15:00 PM
Vicky Boyd

The University of Massachusetts' Fruit Program has received a U.S. Department of Agriculture specialty crop block grant to study the feasibility of containment or tunnel spraying in orchards.

The research is in conjunction with the Massachusetts Fruit Growers' Association,

A Lipco Tunnel Sprayer, which was purchased with the grant, uses a tunnel or tent that covers the row of spray nozzles, capturing off-target material and recirculating it.

In a handful of apple orchard trials conducted so far, the tunnel sprayer captured and recirculated nearly 25 percent of a dilute 100-gallon-per-acre material, says Wesley Autio, a pomology professor at UMass in Amherst who's leading the trials.

They will compare the Lipco sprayer to a conventional airblast sprayer in drift trials this season.

Next season, Autio says he plans to conduct efficacy trials most likely looking at apple scab control. The trials will pit the Lipco sprayer against an airblast sprayer.

The tunnel sprayer can straddle about 8-foot-wide tree rows, kind of like a two-sided air-curtain sprayer.

It also can move over about 12-foot-tall strees.

After the first test pass, Autio removed the nozzles that came on the machine and replaced them with TeeJet AITX ConeJet Air-induction Nozzles that produce a greater flow at lower pressures.

At 100 psi, these put out 0.467 gallons per minute. So for the 16 nozzles on the Lipco, the output was 7.5 gpm or 95 gallons per acre.

"Results were spectacularly better," Autio said in a press release.

Even with a reasonably strong breeze that parallelled the row, there was virtually no drift.

Of the 95 gallons per acre that were applied, 21 were recaptured. The net result was an application rate of 74 gallons per acre for full coverage.

The Lipco also is much quieter when operating compared with an airblast.

But Autio says the sprayer comes with a few caviats: It is much taller than conventional sprayers. It also is more difficult to manage behind a tractor and will take some adjustments and practice.

He says one person has been driving the machine in most of the tests and after some practice has become quite adept at positioning it over the trees.

Mirrors placed on the side of the tractor may help the driver keep tabs on the sprayer that's being towed behind.

The manufacturer recommends speeds of 3 to 4 mph, but Autio says half-jokingly actual speeds depend "on how adventurous you are."

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