Austrian pine is a commonly planted urban tree, often seen along roads and sidewalks for its superior salt tolerance. However, the needle and shot blight disease Diplodia tip blight caused by the fungus Diplodia pinea, has limited the modern use of Austrian pine because of its disfiguring nature. Interestingly, when the pathogen attacks the stem of trees, the phenomenon of systemic induced resistance (SIR) is triggered and the tree exhibits increased resistance against further D. pinea stem infections. This project focuses on both molecular and ecological aspects of the SIR, by examining systemic signaling within the plant and the impact of varying environmental conditions on the resistance reponse. We hope to to gain insight in how trees defend themselves against pathogenic and abiotic stresses so that more informed and environmentally conscience management practices can be implimented.