Inhibitory efficacy of different essential oils against storage carrot rot with antifungal and resistance‐inducing potential

Abstract

AbstractThe inhibitory effects of essential oils (EOs) derived from coriander, lavender, geranium, thyme, savoury and eucalyptus were assessed against Sclerotinia sclerotiorum, the causal agent of carrot white mould. All EOs showed antifungal activity against the pathogen in vitro and in vivo. In addition, all EOs markedly increased 6‐methoxymellein in the treated carrots. The EOs of thyme and savoury were found to be more effective than other tested EOs. The enzymatic tests showed that thyme and savoury EOs were more able than lavender EO to significantly increase the level of chitinases, peroxidases, β‐1,3‐glucanases, polyphenol oxidase, peroxidase and phenylalanine ammonia‐lyase in the treated carrots, indicating that the EOs of thyme and savoury have potential to be considered as effective inducers of resistance against carrot white mould. In this study, all EOs inhibited myceliogenic and carpogenic germination of sclerotia at concentrations 1 and 10 µl/ml sterile distilled water, respectively. After gas chromatography/mass spectrometry, major component in the thyme EO was found to be thymol (39.15%) followed by p‐cymene (13.85%) and carvacrol (10.36%), while in savoury EO were carvacrol (41.9%), γ‐terpinene (17.38) and p‐cymene (11.25%).