This research investigated how a bacterial disease affects the natural fungal communities living on and inside olive tree branches. The study reveals that disease-causing bacteria can dramatically change which fungi are present, with different effects depending on the olive tree variety. Understanding these complex interactions could help develop better disease control strategies for olive growers. Impacts on everyday life: • Helps farmers choose olive tree varieties that better resist disease • Could lead to more effective and natural disease control methods • Improves understanding of how to maintain healthy olive orchards • May reduce crop losses and improve olive oil production • Contributes to more sustainable agricultural practices