Abstract: Storage diseases cause significant losses in pome fruit production and are caused by a plethora of different fungal pathogens that are already present on the fruit at the time of harvest. Due to the diversity of fungal diseases and the extremely high requirements of consumers and retailers regarding the fruit quality, integrated fruit production requires regular interventions with plant protection agents and strategies. Pome fruit production thus requires a large input of plant protection agents (Spycher & Daniel, 2013) and consequently has ample potential for improving plant protection measures and developing low-risk applications. In addition, authorities in Switzerland and several other European countries demand a reduction of health and environmental risks caused by plant protection agents of at least 50% (Bundesrat, 2017). To achieve this goal and maintain the production of high-quality apples, fruit growers need information and advice on designing and operating innovative, sustainable and reliable production systems (Gölles et al., 2015). Therefore, as an alternative to chemical-synthetic fungicides, we are assessing the potential of naturally occurring yeasts as antagonists of apple storage diseases.Yeast-like fungi have been identified as effective antagonists of fungal plant pathogens, but only few yeast species were developed as commercial plant protection products so far. It is our aim to isolate and identify antagonistic yeasts, to characterise the modes of antagonism of the strongest antagonists against plant pathogens, and to assess their potential as plant protection agents against apple storage diseases in the field. Ultimately, it is our goal to establish sustainable apple production systems that require substantially less chemical-synthetic pesticides and result in significantly lower residues on apples.