Fungicides are widely used in conventional agriculture to control plant diseases. Prolonged usage often poses health problems as modern society is becoming more health-conscious. Penicillium digitatum, the cause of citrus green mould, is an important postharvest pathogen which causes serious losses annually. The disease is currently managed with synthetic fungicides. There is, however, a growing concern globally about the continuous use of synthetic chemicals on food crops because of their potential effects on human health and the environment.