Author
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Derksen, Richard |
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Submitted to: New York State Vegetable Conference & New York Stateberry Growers Meeting
Publication Type: Proceedings Publication Acceptance Date: 2/10/1998 Publication Date: N/A Citation: N/A Interpretive Summary: With increasing concern regarding spray drift and keeping materials on target, it is important to update application techniques to minimize off-target contamination and waste of pesticide. A coalition of educators, research scientists, industry and regulatory officials have recently proposed a standardized set of spray drift and buffer zone definitions. The basic causes of drift, such as droplet size and weather conditions, and practical techniques for minimizing drift problems are discussed in this manuscript. New research is evaluating the effectiveness of drift reduction alternatives. Studies conducted by ARS and Ohio State University engineers showed that the effectiveness of these new nozzles varies but that they do produce fewer downwind deposits than traditional nozzles. The latest advances in air-assist and electronic technology that can reduce spray drift and improve on-target efficiency are also presented. As an alternative to purchasing new machines, adding sprayer controllers, replacing pressure gauges, and paying particular attention to nozzle selection and positioning on the boom can help update existing sprayer. Technical Abstract: With increasing concern regarding spray drift and keeping materials on target, it is important to update application techniques to minimize off-target contamination and waste of pesticide. Most drift problems are related, in one way or another, to droplet size. Small droplets may reach terminal velocity, and therefore be more susceptible to wind movement, within only a few inches of a nozzle. While larger droplets reduce the risk of drift, the drift control needs must be balanced with the needs pertaining to spray coverage. Spray nozzle manufacturers have begun to introduce nozzles that claim to reduce spray drift. These nozzles essentially claim to reduce number of small droplet produced in the spray stream. 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 nozzle designs reduced 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. However, droplet size measurements and wind tunnel evaluations showed that reducing the operating pressure and using larger orifice nozzles were also effective in reducing the spray drift potential. As an alternative to purchasing new machines, adding sprayer controllers, replacing pressure gauges, and paying particular attention to nozzle selection and positioning on the boom can help update existing sprayer. |
