This study examined the ability of essential oils (EOs) obtained from the Australian native plants, lemon myrtle (Backhousia citriodora) (LM) and lemon scented tea tree (Leptospermum petersonii) (LSTT) to inhibit the in vivo growth of Penicillium digitatum in citrus fruits. The main constituent of LM and LSTT EOs was citral at 85 and 64%, respectively. Citral was included for comparison. Oranges dipped for 120 sec in EO solutions showed less fungal wastage compared to control with efficacy being LM > pure citral > LSTT, with 1000 μL L−1 LM EO the optimal treatment. The greater response of LM over LSTT EO was attributed to its higher concentration of citral but the greater effect over citral suggested some minor constituent(s) of LM EO also had antifungal activity. While the 120 sec dips caused severe rind injury, a 30 sec dip in 1000 µL L−1 LM EO generated only slight injury and inhibited fungal wastage in Valencia and Navel oranges, mandarins and lemons. A 10 sec dip did not cause rind injury but was less effective for mould inhibition. The findings suggest LM EO as an alternative to synthetic fungicides to inhibit wastage in citrus during storage, particularly for organic produce.
Rahman, M., et al. (2022). “Lemon myrtle and lemon scented tea tree essential oils as potential inhibitors of green mould on citrus fruits.” The Journal of Horticultural Science and Biotechnology: 1-10.