Hazelnut is an economically valuable nut crop worldwide which can be used in various fields for its fruits, oil, bark, leaves, and husks. Because of the limited genetic diversity and the lack of advanced chemical control practices, insect pests and diseases represent major constraints for hazelnut production in the region. The demand for decision support systems and crop forecasting models is thus on the rise. Reliable simulation tools are needed to timely identify situations of risk and to quantify expected yield, as well as yield losses due to biotic stresses and their impact on crop quality. The aim of this project is to provide reliable simulation models, targeted to predict hazelnut pests and disease epidemics and to quantify associated yield losses and quality-related defects. The project will start with the characterization of the main hazelnut growing systems in Turkey. Data collation activities will be performed, aimed at the harmonisation of different types of data and pest/disease models already developed for other tree crops. Disease emergence, dynamics of pest population, impact of hazelnut diseases and pests will be modelled and investigated through the development and the integration of different approaches and tools. The impacts caused by pests and diseases will be assessed, both aiming at improving actual yield forecasting activities including losses due to pests and diseases, i.e. for the coming harvest season, and for new assessments of future climate change scenarios. The developed pest and disease models will be used to support tactical decisions, to forecast yield losses during the growing season and for scenario analyses according to different climatic scenarios. The models will be applied in Turkey, which is the top hazelnut producing country. Their application in other hazelnut producing areas will be evaluated during the project development.