Postharvest Application of Some Essential Oils for Controlling Gray and Blue Moulds of Apple Fruits

Worldwide gray mould caused by Botrytis cinerea and blue mould caused by Penicillium spp. are the most important diseases attacking apple fruit during storage. Evaluating the effects of some essential oils i.e., eucalyptus, lemon grass and thyme on linear growth and spore germination of pathogenic fungi. Moreover, their efficacy on gray and blue moulds incidence of apple fruits was tested. All treatments significantly reduced the linear growth and spore germination of both tested fungi. Essential oils of eucalyptus, lemon grass and thyme at a concentration of 0.6 and 0.8% completely inhibit the linear growth and spore germination of B. cinerea and Penicillium sp. except that lemon grass at 0.6%. Sterilized water containing essential oils of eucalyptus, lemon grass and thyme at different concentrations, i.e., 0.0, 0.6 and 0.8% (v/v) were tested to study their effect against gray and blue mould incidence of apple fruits. Results indicated that all treatments significantly reduced the disease incidence and rotted part tissue (Disease severity). The most effective treatment was eucalyptus and thyme at 0.8%, which reduced the disease incidence more than 83.8 and 82.7% and rotted part tissue by 85.9 and 88.5% for gray and blue moulds, respectively. The highest reduction was obtained with eucalyptus and thyme at concentrations of 0.6% and lemon grass at 0.8% which reduced both diseases incidence and rotted part tissue more than 74.0 and 75.8%, respectively. Meanwhile, other treatments showed moderate effect. It could be suggested that essential oils could make them an excellent treatment for controlling postharvest diseases of apple fruits.