The disclosure relates to a method for treating a plant infection caused by a fungus of the class ascomycetes, comprising applying to the plant a combination of tea tree oil (TTO) and a synthetic fungicidal compound selected from the group consisting of triazole-based demethylation inhibitors (DMIs) and strobilurin-based Quinone outside Inhibitors (QoIs), wherein the infection is selected from the group consisting of banana plant Black Sigatoka, carrot alternaria, tomato powdery mildew, and pepper powdery mildew.
