Abstract: In the frame of the PEPS project supported by the French Ministry of Agriculture, five plant resistance inducers (PRIs) were tested both in orchard and in controlled conditions. The first work package of the project was to screen in laboratory about thirty commercialized products in order to select the five most efficient apple defence activators. The products are then tested throughout the PEPS network of experimental orchards for their ability to protect against apple scab and storage diseases. In parallel to orchard trials, several studies are performed in controlled conditions in order to identify factors that can influence PRI efficiency and to study additional properties of the products. This paper is a mid-term review of the project.