The effect of Lamiaceae plants essential oils on fungal plant pathogens in vitro

Abstract

Fungal pathogens Alternaria spp., Botrytis spp. and Colletotrichum spp. cause a significant loss of horticultural crops and their yield annually. The most convenient way for controlling diseases caused by these pathogens is the use of chemical fungicides. However, current practices still result in soil, water and air pollution, contribute to the loss of biodiversity and climate change, also are harmful to human health. Therefore, there is a growing demand for environmentally friendly plant protection methods. Herbs, especially, volatile oils, are a natural source of active ingredients. The findings of antimicrobial and antifungal activities, low toxicity, and biodegradability of essential oils make them potential for use in plant protection against pathogens instead of chemicals. This research aimed to evaluate the ability of Lamiaceae plants essential oils to suppress the growth of Alternaria spp., Botrytis spp., and Colletotrichum spp. in vitro. The study was carried out at the LAMMC Institute of Horticulture, Lithuania. Essential oils from lavender (Lavandula angustifolia) and thyme (Thymus vulgaris) were obtained by hydrodistillation and poured to potato dextrose agar medium at 200 1,000 L -1 concentrations. The radial colony growth of each pathogen measured after placing mycelial plugs of each fungus on Petri dishes. Results demonstrated that thyme essential oil significantly suppressed the growth of all three investigated fungal pathogens at concentrations starting from 400 L -1 7 days after inoculation as no growth of the pathogens observed. Meanwhile, lavender essential oil had lower antifungal activity than thyme. The most significant concentration of lavender essential oil was 1,000 L -1 . To conclude, thyme essential oil showed high antifungal activity, and lavender essential oil showed moderate antifungal activity for our tested horticultural crop fungal pathogens. Both oils can be applied as one of the eco-friendly ways to control plant pathogens.