Spray droplets are carried by prevailing winds. The area of concern relative to spray drift is associated with spray droplet deposits and associated damage to sensitive or potentially sensitive areas. Diffusion or vapor drift is primarily of concern from applications of phenoxy-type or other highly volatile herbicides. Spray drift from the application site has potential for off-target damage, environmental impact, wasted chemicals, and inadequate pest control in the application zone. Environmental conditions, and spraying practices and equipment are the primary factors contributing to spray drift.
Wind velocity is the dominant environmental condition affecting spray drift.
Droplet size, height of flight, aircraft speed, and boom length are the dominant spraying and equipment factors affecting spray drift.