Managing the size of spray droplets is a critical step in reducing spray drift. Some key things to know about droplet size:
Small droplets, big problems. The smaller the size of the droplet, the less it weighs and the easier it drifts.
Bigger is better. Heavier droplets fall more quickly and are less affected by air movement.
Little changes go a long way. Even small changes in droplet diameter make big differences in droplet weight. An increase in droplet diameter from 150 microns to about 190 microns doubles the droplet weight. An increase in droplet diameter from 150 microns to about 240 microns increases the weight four times. Doubling the diameter to 300 microns increases its weight, and also its volume, by eight times.
Size classification. The American Society of Agricultural and Biological Engineers developed a droplet size classification system. The classes range from extremely fine to ultra coarse based on drift values.
Check the label. The recommended droplet size category to use with a particular pesticide may be listed on the product label. An example of a label statement would be: “Apply with 10 or more gallons per acre using a nozzle producing a coarse droplet.” Nozzle selection and pressure can then be based on the nozzle manufacturer’s droplet size category charts.
Typical low-drift nozzle. Usually, low-drift nozzles will produce spray droplets in the medium to extremely coarse range, while reducing the number of fine droplets.Source: NSF Center for Integrated Pest Management, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.