Types Of Drift; Factors Affecting Drift - Bestway field-pro IV 1600 Operator's Manual

Although some products have a greater tendency to drift than others, due to their volatility, the
potential for drift exists with any chemical. Unfortunately, with the advent of genetically altered
crops like Roundup Ready soybeans, and Liberty Link corn, the potential damage that can occur as
a result of chemical drift is greater than ever before.
In order to make informed decisions about nozzle selection and operation, an applicator must
first be knowledgeable about droplet size and the causes of drift.

Types Of Drift

•
Particle drift - Particle drift is due to off-target movement of spray particles during
application. This can happen with any chemical.
•
Volatilization drift - Volatilization drift is due to a chemical's ability to volatilize after an
application has been made. Therefore, it has more to do with the chemical's characteristics
than the sprayer or spray pattern.

Factors Affecting Drift

•
Wind speed and direction - Since chemical particles can be carried by the wind, stronger
winds are obviously more likely to cause drift. A doubling of wind speed generally doubles
the horizontal distance droplets will travel.
•
Relative humidity - In general, the lower the humidity, the greater the drift potential.
•
Air temperature - In general, higher temperatures mean increased drift potential.
•
Droplet size - With most chemicals, controlling spray droplet size is a key factor in
controlling drift. The smaller the droplet, the slower it will fall, the faster it will evaporate
and the further it will drift horizontally, particularly if winds are also a factor. Droplet
size is primarily determined by nozzle orifice size, spray angle and spray pressure.
Therefore, an increase in nozzle orifice size and/or a decrease in pressure is one way to
increase droplet size and decrease the potential for drift.
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