Spray droplet adhesion is a consequence of dynamic interactions of formulants within the spray droplet during flight and on impact, physical properties of the droplet (size and velocity), leaf surface morphology and leaf orientation. The objective of this study was to improve on a universal adhesion model incorporating the above factors. The previous spray droplet adhesion model has been extended to include droplet size (ranging from 180 μm to 1000 μm) and droplet velocity (0.63 ms-1 to 2.82 ms-1 at impact), and made more robust by increasing the number of formulations (dynamic surface tension of droplets at impact range from 20.7 to 72 mN m-1), the types of leaf surfaces (20% acetone contact angles on the leaf surfaces range from 61° to 124°), and the number of droplet impact angles (leaf angles from horizontal to 67.5°). In this study, contact angles using 20% acetone:water accounted for 95% of the differences between the leaf surfaces studied compared to 76% previously observed with water only. The present universal model explains 74% of the deviance. The current model's capabilities and limitations are discussed in relation to the physical parameters measured and observed.