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Nozzles and Additives To Reduce Drift

Mark Mohr
Extension Specialist
Department of Agricultural Engineering
(217) 333-9418; mmohr@illinois.edu
Mark Mohr

Spray drift can have severe economic and environmental consequences. The nozzles applicators use and the additives in the spray are important factors that can be used to control spray drift. Various nozzle designs and drift-control additives are available to help applicators reduce drift.

Newer Nozzle Designs

The air-induction or venturi nozzle design is one tool to reduce drift. Though several designs exist, they work similarly, using a mixing chamber combined with a venturi that draws air into the spray, reducing pressure at the tip and resulting in larger droplets that reach their target more effectively than do small droplets.

The mixing or “turbulence” chamber is a feature found in many newer nozzle designs. The Turbo Teejet™ uses a turbulence chamber to create larger droplets and uniform patterns. One of the earliest pre-orifice designs was the “drift guard” or “drift-reducing” flat fan nozzle.

figure 1

Figure 1. Nozzle type and drift reduction additives will influence
spray breakup and droplet size.

Because each nozzle type creates a different range, or spectrum, of droplet sizes, it is important for the applicator to match the nozzle to the job. Labels and nozzle catalogs have standard terms that refer to specific droplet spectra, so both documents are important references. If a label calls for “coarse” droplets, nozzles should be used that produce “coarse” droplets. Droplet spectra are categorized according to standard ASAE S572. The droplet spectrum from a nozzle will depend on operating pressure, but in general, the droplet spectrum gets larger as the application goes from drift-reducing flat fan to Turbo Teejet to venturi nozzles. The final authority on droplet size is the pesticide label.

Drift Reduction Additives

Drift-reduction additives are adjuvants to increase droplet size. Research and field use has shown they can greatly reduce spray drift when used with traditional nozzles. It is important to compare the recommended droplet size on the pesticide label with the droplet size the nozzle will produce. Nozzles considered “drift reducing” already produce larger droplets, so those who want to use drift-reduction additives along with drift-reducing nozzles may be concerned about the effect on spray pattern.

Taking a Look

New nozzle designs and spray additives can give applicators good options in controlling drift. Knowing how the new designs and additives interact should be important for both pest and drift control. The objective is to evaluate the performance of several newer nozzle designs when they are combined with drift-reduction additives. This is done by evaluating nozzle and additive performance by looking at the spray pattern and resulting deposition uniformity.

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