At what droplet size does spray drift begin to become a concern?

Spray drift is a critical consideration in aerial application, as it refers to the unintentional movement of spray particles away from the target area, which can lead to contamination of non-target areas and unwanted environmental impacts. The concern for spray drift typically begins with smaller droplet sizes because they are more susceptible to being carried away by wind or atmospheric movements.

Droplets that are 200 microns and below are considered to be at a size where drift becomes a significant risk. This is due to their lighter weight and larger surface area-to-volume ratio, making them more prone to evaporation and wind dispersal. As droplet sizes decrease, they lose the momentum required to reach the target effectively, thus increasing the likelihood that they will be affected by external factors like wind. The 200-micron threshold serves as a guideline for applicators to minimize drift and is critical in ensuring that the application of pesticides and other chemicals is both effective and environmentally responsible.