Influence of spray characteristics on potential spray drift of field crop sprayers: A literature review

• Spray characteristics with relevant influence on spray drift are identified.
• The aggregation of literature data leads mostly to convergent arguments and behavior.
• The need for global descriptors of sprays including spatial distribution of droplets is highlighted.

Spray drift is a practical consequence of agricultural spraying operations. Because of the agronomical and environmental impacts of this phenomenon, drift has been widely studied and extensive information is available. Here we present a literature review on the relationships between global physical descriptors of agricultural sprays, air conditions and resulting drift, generally studied in wind tunnels. Basic physical factors are droplet size, droplet velocity, and the physicochemical characteristics of the sprayed product. When possible, data available in the literature are collated to draw trends. Contradictory information sometimes appears especially regarding droplet velocity and drift control. The main physical factors consist generally of medians such as Volume Median Diameter (VMD or Dv50) that do not always represent the heterogeneity of a spray and especially the spatial distribution of particle size and velocity. Technological parameters such as nozzle height, spray angle, travel speed are then related to initial physical factors and their contribution to driftability of sprays.