Attention to fundamentals 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, says Brian Storozynsky, sprayer technology specialist with the AgTech Centre in Lethbridge, Alberta. Some of these fundamentals include nozzle choice, boom height and water volume.
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.
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."
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 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."
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 technical assistants (TAs) throughout the province. Contact an AEFP facilitator or regional team leader or visit the AEFP Web site at www.AlbertaEFP.com for information on TAs in your area.
This article is reprintable with credit to AEFP as follows "Reprinted courtesy of the Alberta Environmental Farm Plan Company; www.albertaEFP.com".
