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Effective spraying is key

By Staff | Jul 25, 2016

ANDREW LANDERS, an ag engineer at the Atkins Center for Sustainable Future at Cornell University, led an all-day event on effective orchard and vineyard spraying at the Iowa State University horticulture farm near Ames. Landers was demonstrating how a key factor to efficient spraying is calibration.

AMES – A recent all-day workshop aimed to help orchard and vineyard owners and producers understand a more effective way to apply pesticides.

Presenter Andrew Landers, an ag engineer at the Atkinson Center for Sustainable Future at Cornell University, offered insights based on trials he conducted at the college.

“The challenge is to improve (droplet) deposition, reducing drift, producing quality fruit and public profile and perception,” said Landers.

Finding the proper sprayer doesn’t necessarily mean an orchard or vineyard grower will have solved all pesticide application issues.

“It’s not just the machine, it’s several things,” said Landers. “It’s productivity, environment, management, weather, the spraying system, efficacy, time availability and safety.”

The operator will also make a big difference on effectively spraying.

“The skill, attitude to work and management of the operator as well,” he said.

The target of effective spraying means looking at a wide range of issues, Landers said, including the variety, growth stage, crop conditions, canopy architecture, block size, row width, penetration, deposition, acceptable coverage and an acceptable disease and insect threshold.

Landers said the art of spraying is quite simple, but the number one problem he sees in orchard and vineyard spraying is matching chemical rates to the target.

“If you’re under-dosing you are getting poor control,” Landers said, “if you are over-dosing you are dealing with cost, residues and creating resistance.”

The second problem pesticide applicators encounter is meeting expectations and requirements of legislators, neighbors and the market.

“We need to reduce drift,” he said. “We need to be seen doing it right and maintain the right to spray.”

Air assisted sprayers

One popular type of sprayer used in orchards and vineyards is an air-assisted sprayer.

Two distinct fluids and fractions are used while spraying, Landers said – air and liquid.

A major attraction to these types of sprayers is to cover a canopy with the proper air speed and air volume and direction.

New technologies improve this task, but when using an air-assisted sprayer, Landers said, operators must determine the detection of the target (size, density and stage); adjust the quantity of liquid or air and always keep checking for correct operation.

“Young producers are excited by new technology, not so much are those legacy sprayers,” he said.

Backpack spraying

Landers said backpack spraying is an economical sprayer system that can be purchased at most local farm-supply stores, but they are poor sprayers with disadvantages such as small fill holes and poor back-straps.

“Buy one that features a larger fill hole and better straps,” said Landers. “Backpack spraying is a young man’s job.”

In addition to backpack spraying being a high-labor intensive activity, Landers said it is a cheaper form of spraying, but often without a pressure gauge.

“You will need to buy pressure regulation valves, which will regulate the flow rate through your nozzle and the output should remain constant while the tank pressure changes,” said Landers. “They will help even out the flow.”

Another issue that comes with backpack spraying is control of forward speed.

To assist with that, he suggests getting an app for a smartphone to help set a walking speed or conduct a test run using dye and water.

Because hand-pumping a backpack sprayer can get tedious, Landers said an alternative would be using gas-driven or battery-pack units.

Mounted sprayers

If a producer would like to mount a sprayer onto their ATV or UTV machines, Landers advised buying a machine that will penetrate the crop.

For example, something with leaf blower-like technology. This technology, Landers said, is ideal for backpack spraying, too.

Canopy sprayers

Landers described canopy sprayers as multi-head sprayers with rotary atomizer or hydraulic nozzles to generate droplets. Large fans then generate air to transport the droplets to the canopy.

Air blast sprayers

Another type of sprayer that uses a large fan is an air blast sprayer.

With these sprayers, Landers said liquid is fed into a rapidly moving air stream. The liquid is then shattered into droplets that are carried into the canopy through the air stream.

Landers said advantages to these sprayers include affordability, versatility, simplicity to operate and maintain and maneuverability.

But disadvantages include the fact they have a “lower than intended deposition, great amount of drift, there is a visual plume while spraying – so you have to deal with public perception and traditional designs are single row machines,” according to Landers.

Tower sprayers

When comparing tower sprayers to air blast sprayers, Landers said the towers will help get the spray to the target.

“Air requirement is the same due to no need to blow it upward like the air blast sprayers, but with more of an even flow,” he said.

Tunnel sprayers

Landers said these sprayers go over the crop, creating a tunnel.

The unused spray (or drift) is captured back into the machine and is recycled.

“These will offer a 90 percent reduction in drift,” he said. “If you are very close to your neighbors, this is one sprayer to consider.”

However there are also some disadvantages to tunnel sprayers.

The cost of these sprayers, Landers said, can run $48,000 for apple producers and $18,000 for a one-row, or $25,000 for a two-row vineyard sprayer.

Another disadvantage is difficulty in turning on short headlands.

After choosing the right type of sprayer, Landers recommends paying close attention to nozzles.

He suggested getting rid of the old coffee can full of old nozzles and opting for the modern, plastic nozzles.

These nozzles are often color-coated so they are easily identified.

He warned about taking care when cleaning a plugged nozzle.

“Don’t use anything larger than the size of the nozzle, like a paper clip in size,” Landers said. “Maybe carry a can of air or use a better filtration system because a blocked nozzle comes from poor agitation or from poor filtration systems.”

To help with these issues, Landers recommends having spare nozzles for those times with one becomes blocked and simply change it out.

Calibration is a simple way to achieve a successful pesticide application.

Landers said it should be done before spraying and possibly again mid-season.

An end-of-season calibration, Landers said, can be helpful to compare to the information found on your end sheets.

“Although calibration does take some time and is hardly anything exciting, it definitely needs to be done,” said Landers.

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