Genetic resources are an important source of traits for adaptation to climate change and resistance against diseases. With the support of the Swiss Federal Office for Agriculture, the pool of Swiss pome fruit genetic resources has been streamlined through molecular and pomological analyses to approximative 1200 apple and 600 pear heirloom accessions. Through analyses of fruit and tree characteristics including screening for disease resistance, fresh fruit and processed product quality, interesting apple accessions for breeding were identified. The final aim is to use these genetic resources to develop new apple cultivars with a broader genetic base and advantageous traits. In this study we present our results from the fire blight susceptibility screenings and crosses with one parent from genetic resources and the other parent from modern advanced breeding clones and cultivars. About 15% of 450 tested heirloom apple accessions showed “very low” or “low” susceptibility to fire blight in shoot inoculations, while about half of the 13 accessions tested for floral resistance showed also a low relative susceptibility to fire blight. First offspring from crosses scored “good” to “very good” in the overall evaluation of the first-year selection step, this showing the potential of genetic resources also for breeding purposes.