Apple cultivars show biennial fluctuations in yields (alternate bearing). The phenomenon is induced by reduced yields in one year due to freeze damage, low pollination rate or other reasons. Consequently, trees develop many flower buds that blossom in the following year. The many flowers lead to a high number of small fruits that won’t be accepted on the market. Endogenous factors (phytohormones and carbohydrate allocation) subsequently establish the biennial cycle. The alternate bearing cycle can be broken by reducing excessive flowers using either chemical or mechanical means. Currently, automatic thinning systems are treating the trees uniformly despite the fact that neighboring trees can have a very different number of flowers resulting in different thinning requirements. In order to solve this problem the joint R&D project OptiThin has been started three years ago. The aim of OptiThin was to develop a system that adapts thinning intensity individually to each tree, and reduces the flowers efficiently and environmentally sound. In the result, OptiThin comprises a set of new technologies including: a) a stereo camera with software for real-time determination of flower density per tree; b) a shock absorbing camera platform; c) a mobile geographic information system with a decision support tool to calculated optimum thinning intensity based on current flower density and ancillary data (e.g. yield, soil); d) a mechanical thinning unit which is controlled in real-time. It was shown that adaptive management of excessive flowers could improve yield of marketable fruits and that environmental friendly mechanical thinning – without chemicals – is feasible.