The Essential Oils of Thyme, Sage and Peppermint against Strawberry Anthracnose

Strawberry Colletotrichum spp. is a significant strawberry pathogen with yield losses of up to 50 %, due to agrometeorological conditions change its spread in a temperate climate is growing. The most convenient way for controlling diseases is use of chemical fungicides. The demand for alternative measures for biological protection is growing because of the increasing pathogens resistance and pesticides harm for human and environment. Thyme, sage and peppermint are a source of natural antioxidants and biologically active compounds. The findings of antimicrobial and antifungal activities of these plants, low toxicity and biodegradability of essential oils (EO) make them suitable for biological protection against pathogens. This study aims to evaluate the inhibition of Colletotrichum spp. by thyme, sage and peppermint EO in vitro and in vivo, to determine chemical composition of EO. The results revealed that the dominant compound of thyme was thymol 41.35%, peppermint – menthone 44.56%, sage - α-thujone 20% and camphor 25%. Thyme EO inhibited Colletotrichum spp. completely above 200 μL L⁻¹ concentration in vitro. Peppermint and sage EO slightly reduced mycelial growth of Colletotrichum spp. However, in vitro, results are very promising for biological control. The in vivo experiments showed that Colletotrichum spp. disease severity 4 days after inoculation were suppressed by 1000 μL L⁻¹ peppermint EO (12.5%) and 800 μL L⁻¹ thyme (4.2%) compared with control. Our findings could potentially help to manage Colletotrichum spp.; however, the in vivo assay showed that EO efficacy was relatively low on tested concentrations and should be increased.