This study examined the different fungi living in elm tree shoots to understand why some elm species are more resistant to Dutch elm disease than others. Researchers found that healthy elms host fewer fungal species compared to diseased trees, and that fungal communities differ significantly between elm species and urban versus rural locations. Importantly, a fungus called Sphaeropsis ulmicola appears to be a significant emerging threat to elms in northern Europe, separate from the classic Dutch elm disease pathogen.