The fundamental principles of good application are the same whether a biopesticide or chemical pesticide is being used. However, there is a view that biopesticides are more sensitive to application. A good application technique should result in the minimum amount of biopesticide being used, which requires that the dose is delivered to the right location at the right time and in the right form. This chapter discusses the factors that are important in achieving this. The chapter concludes that calibration is important and automation should bring benefits. The biopesticide mode of action, the pest or disease and the crop structure are important to understand. Without this, growers will continue to try to visibly cover every part of the plant with spray resulting in high levels of waste and poorer control than optimum. More research on the interaction between performance and application is needed to enable the principles of IPM to be implemented.