Spray drift occurs during pesticide applications, when droplets move through the air from a target site to a non-target site. This can expose people, wildlife, and other plants to pesticide residues. However, in order to minimize spray drift, we must first understand what causes it.
The spraying equipment used in the field can have a large impact on spray drift. During applications, pesticide droplets flow through hydraulic nozzles. Each nozzle is classified according to its spray quality, which produces different sized droplets.
Smaller droplets provide better coverage, but tend to evaporate and drift onto non-target areas. Larger, coarse droplets are not easily moved by the wind but are more likely to run off the target area and provide less coverage.
Weather conditions, natural and man-made physical barriers, and the type of target site are additional factors that will influence spray drift.
Research has shown that for most applications, some spray drift is expected. This is not unacceptable, as very small amounts of most pesticides will generally not affect non-target sites. However, great precautions should be taken to minimize drift where highly sensitive sites occupied by humans, non-target crops, and wildlife habitats are known to be close by.
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