Controlling Drift from Chemical Sprays

Attention to Fundamentals is Key

With safety, liability and environmental concerns driving new developments, producers today have more options than ever in the ongoing battle against the airborne drift of chemical sprays. However, a well-rounded line of defence against spray drift still comes down to the fundamentals, according to Brian Storozynsky, sprayer technology specialist with the AgTech Centre in Lethbridge, Alberta. Some of these fundamentals include nozzle choice, boom height and water volume.

Nozzle considerations

Popular nozzle options today include standard, extended range, pre-orifice, combo jets, and single and twin air induction nozzles, with a range of models within each type. Few nozzle types have been found to reduce spray drift as effectively, however, as venturi — or air induction — nozzles.

An AgTech Centre study found that low pressure venturi nozzles reduced drift by 35 to 60 percent compared to conventional, pre-orifice low drift nozzles when operated between 25 and 60 pounds per square inch (psi). The same study found that high pressure venturi nozzles reduced drift by 60 to 90 percent compared to pre-orifice nozzles when operated at 40 to 120 psi.

Boom height

When it comes to deciding on boom height, the answer is simple, says Storozynsky: the lower the height, the lower the drift. “Of course, you don’t want to go too low or you won’t get adequate coverage. That’s why we generally recommend a minimum operating height of around 18-20 inches. That height has become the target for a lot of producers because it usually ensures adequate coverage with minimal drift.”

Water volume

The basic rule with water volume is the higher the water volume, the lower the drift, says Storozynsky. However, this rule of thumb only holds true when comparing volume within a specific nozzle type — it is not true when comparing the efficacy of different nozzle types to each other. “For example, if you were to compare an extended range nozzle set at 10 gal/ac to a venturi nozzle set at five gal/ac, you would find that the venturi nozzle would produce less drift.”

Available Assistance
Information and assistance on managing spray drift, as well as a number of other on-farm environmental practices, is available through a strong network of EFP Technicians throughout the province.

This article may be reprinted with the credit: Alberta Environmental Farm Plan
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