The effect of plant essential oils on citrus green mold

Using natural plant products has become more important as viable alternatives to control postharvest diseases. The effect of four essential oils of medicine plants including Thymus vulgaris, Cuminum cyminum,Allium sativum and Aloe vera were tested (100, 200, 300, 400ppm) in vitro and in vivo (200,300,400 ppm) for their fungal inhibitory percentage and antagonistic properties against Penicillium digitatum. Plant essential oil extracted by hydro distillation using a Clevenger-type, and minimal inhibition concentrations (MIC) was determined using agar dilution method. In vitro inhibitory effects of the plant extracts showed maximum percent inhibition (99.95%) by thyme extract, which also had the best MIC value against P. digitatum. GC-MS analysis of the thyme oils extract led to the identification of 22 different components which carvacrol (2.88%), 60.18% thymol (60.18%), linalool (4.22%), γ-terpinene (6.39%) were found to be the main constituents in T. vulgaris. Thyme essential oil inoculated into wounds with the pathogen stimulated the orange to increase production of phenol compound, catalase and peroxidase activity. Thus, different concentrations of the thyme essential oil are effective on controlling the producing agent of the green mold fungus significantly, and induce resistance to orange by effect on defense enzyme.