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May 20, 2004 New Spray Nozzles Help Reduce Drift Spray drift wastes money, reduces the effectiveness of pesticides and can cause significant damage to surrounding crops, trees and water supplies. Keeping pesticide applications on target is a key to having the maximum impact on weeds, insects and diseases while minimizing costs. “Probably the most important threat from spray drift is the potential damage to other crops in the area,” notes Vern Hofman, agricultural engineer with the North Dakota State University Extension Service. “Some crops, as well as trees and other native vegetation, can be extremely sensitive to herbicides. An unintended application from drift can have devastating results.” New low-drift spray nozzles are available to reduce drift. A producer needs to decide if a low-drift nozzle is right for their spraying needs. One type of nozzle will seldom be the best choice for all situations. It’s best to consider your spraying priorities before choosing a nozzle. Nozzles are relatively inexpensive, but they can be the most important sprayer component you buy. The following are some things to consider:
Low-drift nozzles are designed to produce spray droplets with fewer driftable fines. Larger droplets are produced in a pressure-reducing chamber inside the nozzle and, in some cases, air is added into the droplets. “These nozzles are excellent at reducing drift, but they do not eliminate all drift,” Hofman says. “Caution must still be used when susceptible crops are downwind.” When drift is reduced, coverage may also be reduced or stay about the same as with finer droplets. Spray coverage is usually less because fewer large drops will be deposited on the plant. There will be larger spaces between the spray drops even when the same application rate is used. Systemic pesticides are usually recommended for use with low-drift nozzles. Pesticides that move within the plant usually do not need to cover the entire plant compared to a contact pesticide. Low-drift nozzles may only provide moderate or poor control with contact type pesticides and are usually not recommended for these applications. It is best to read the label for specific restrictions. One of the newer drift-reducing nozzles is the venturi air induction nozzle. It pulls air into the spray nozzle and mixes it with the spray mix. All venturi brand nozzles have the same basic design. They form an air-entrained droplet at lower pressure. The coarse spray contains large, air-filled drops. Very few of the drops are drift-susceptible. Venturi nozzles differ from conventional low-pressure flat fan spray nozzles because they produce drops with fewer fines. Excellent drift reduction, while maintaining good coverage, has been observed using venturi tips. More information on drift reducing nozzles is available in the NDSU extension publication “Choosing Drift-Reducing Nozzles” (FS-919). The publication is available at county extension offices or at www.ext.nodak.edu/extpubs/machine.htm on the Web. ### Source:
Vern Hofman, (701) 231-7240, Vernon.hofman@ndsu.nodak.edu |
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North Dakota State University |
