June 26, 2003

 

New Nozzle Designs Reduce Drift, NDSU Ag Engineer Says

Pesticide spray drift may reduce pesticide effectiveness, cause damage to surrounding crops and trees, and waste money. According to a North Dakota State University Extension Service agriculture engineer, an unintended application to trees and other native vegetation can have a devastating effect.

"An important threat from spray drift is the potential damage to other crops," says Vern Hofman. "Keeping pesticide applications on target is important to have the maximum impact on weeds, insects and diseases while minimizing costs,"

New nozzles produce larger drops which can significantly reduce drift, says Hofman. However, the effectiveness of the application may be reduced as large drops may not provide sufficient coverage for contact type herbicides. "One nozzle will seldom be the best choice for all applications," Hofman says.

According to Hofman, drift-reducing nozzles are recommended for use with pre-emerge and systemic pesticides. The extended range flat fan nozzle was the first of its kind. This nozzle can operate at pressures as low as 15 pounds per square inch (psi) and maintain a uniform pattern. It can also operate at 40 to 50 psi, but will produce a considerable amount of fine drops. At lower pressures it will produce a medium to coarse spray drop.

Another drift-reducing nozzle is the pre-orifice flat fan nozzle. This nozzle contains a metering orifice ahead of the flat fan nozzle, allowing for a pressure reducing chamber in the orifice, Hofman says. The lower pressure produces larger spray drops and less fine drops. The pre-orifice nozzle usually produces a medium to coarse drop size. However, the spray coverage from this nozzle may be slightly less than an extended range flat fan nozzle.

The turbo teejet nozzle contains a pressure-reducing chamber and produces medium to coarse drops similar in size to the pre-orifice flat fan. "The number of fine drops produced is less than what the extended range flat fan nozzle produces at 40 psi, but still provides good spray coverage of the target," Hofman says

The newest drift-reducing nozzle is an air induction nozzle. This nozzle produces a coarse to a very coarse drop with few fine drops. This nozzle is very good at reducing fine drops compared to the extended range flat fan, Hofman says. The nozzle contains an internal metering orifice, an outer nozzle to produce the spray pattern and an air inlet to meter in air. Air is pulled into the nozzle, mixes with the spray and forms air-entrained drops. Most of theses nozzles are designed to operate at pressures above 40 psi while providing excellent drift reduction.

"Canadian research is showing that air induction spray nozzles are able to reduce spray drift similar to a shielded spray boom," Hofman says. "But, it must be emphasized that these nozzles do an excellent job of reducing drift, they do not eliminate all drift. Caution must be used when spraying upwind of susceptible crops."

"Considerable advancements have been made in spray nozzle design," Hofman says. "New nozzles are available to reduce drift and applicators should investigate what’s available and how they might fit into their spraying operation."

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Source: Vern Hofman, (701) 231-7240, vernon.hofman@ndsu.nodak.edu
Editor: Stephanie Renner, (701) 231-8371, srenner@ndsuext.nodak.edu