This research examines a dangerous fungus called Calonectria eucalypti that destroys eucalyptus trees worldwide. Scientists sequenced the fungus’s complete genetic code and tracked which genes turn on during infection, discovering that the pathogen uses different sets of genes at different stages of infection. By identifying key virulence genes and understanding how the fungus attacks plant cells, this research provides a foundation for developing better ways to prevent and manage eucalyptus leaf blight disease.