Effect of citronella essential oil on the inhibition of postharvest Alternaria alternata in cherry tomato

BACKGROUND: Essential oils such as citronella oil exhibit antifungal activity and are potential alternative inhibitors to chemical synthetic fungicides for controlling postharvest diseases. In this study the antifungal activity of citronella oil against Alternaria alternata was investigated. RESULTS: In vitro, citronella oil showed strong inhibition activity against A. alternata. The minimum inhibitory concentration in potato dextrose agar and potato dextrose broth medium was determined as 1 and 0.8 mu L mL(-1) respectively. In vivo the disease incidence of Lycopersicon esculentum (cherry tomato) treated with citronella oil was significantly (P < 0.05) reduced compared with the control after 5 days of storage at 25 degrees C and 95% relative humidity. The disease incidence at oil concentrations of 0.2-1.5 mu L mL(-1) was 88-48%. The most effective dosage of the oil was 1.5 mu L mL(-1), with 52% reduction, and the oil had no negative effect on fruit quality. Scanning electron microscopy observation revealed considerably abnormal mycelial morphology. CONCLUSION: Citronella oil can significantly inhibit A. alternata in vitro and in vivo and has potential as a promising natural product for controlling black rot in cherry tomato. (C) 2014 Society of Chemical Industry