Abstract: This experiment was conducted to study the inhibitory effect of three plant essential oils (eugenol, citral and carvacrol) on Colletorichum acutatum by means of in vitro fumigation and the effect of the strongest inhibitor, eugenol, on the ratio of exosmosis, intracellular nucleic acid and protein contents of C. acutatum. After wounding and artificial inoculation with C. acutatum, loquat fruits underwent eugenol fumigation at 0.5, 1.0, 2.5 and 5.0 μL/L. Disease incidence and lesion diameter were recorded and the effect of this treatment on the fruit quality was also studied. Results showed that all three essential oils demonstrates inhibitory activities in vitro against C. acutatum. Eugenol could inhibit the growth of C. acutatum completely at a concentration of 48 μL/L and cause the leakage of cytoplasm. Compared with the control group, 1 μL/L eugenol could significantly reduce anthracnose incidence to 66.67% and average lesion diameter to 6.41 mm after 6-day storage. Moreover, percentage water loss and vitamin C loss were significantly inhibited (P < 0.05), while no significant changes were observed in firmness, color, soluble solid content, titratable acid or ascorbic acid in loquat fruits (P > 0.05).

Key words: essential oil, eugenol, Colletorichum acutatum, loquat, postharvest anthracnose