The functions of 8 commercial spreaders were evaluated. Dynamic surface tension and the contact angle of 8 pesticide spray solutions were determined both with and without the spreader under field trials. Results of both dynamic surface tension and contact angle measurement show that 1 of the spreaders, A8, was functionless when applied at the recommended concentration. Based on the reduction in the dynamic surface tension, the ability of spreaders to nebulize a spray solution and improve the wettability and adhesion of droplets onto leaf surfaces can be predicted. The spreading and infiltration ability of droplets on target surfaces can also be estimated by contact angle observations.