Submitted to: American Vegetable Grower
Publication Type: Popular Publication
Publication Acceptance Date: May 10, 1999
Publication Date: N/A
Technical Abstract: It makes economic and social sense for growers to be aware of the drift risk potential posed by their application practices. All nozzles produce a driftable fraction. Small droplets are the primary cause of spray drift. Small droplets, those smaller than 150 microns in diameter, become susceptible to wind movement within a few inches of discharge from a nozzle. Drift control must be balanced with the past management needs. While larger droplets reduce the risk of drift, they also reduce the effective spray coverage. Spray nozzles manufacturers have introduced nozzles that they claim to reduce spray drift. There has been little independent research data available to support these claims. Recent studies conducted by USDA-ARS and Ohio State University engineers found that some of these new nozzles do produce fewer small droplets than standard flat fan nozzles. One of these new nozzles designs reduce the percentage of driftable droplets from over 50% for a standard nozzle to less than 10%. Wind tunnel evaluations also confirmed that these drift reduction nozzles produce fewer downwind deposits. There were differences in the amount of drift control provided by the various drift reduction nozzles. These studies also demonstrated that using larger orifice nozzles and reducing the operating pressure was also effective in reducing the spray drift potential. Advances in air-assisted delivery and electronic controls are also promising alternatives for reducing spray drift.