A study on antifungal activity of thymol, eugenol, and 1,8-cineole against Botrytis cinerea Persoon isolated from grapevine (Vitis vinifera Linné)

This study investigated the effects of essential oils thymol, eugenol, and 1,8-cineol for the prevention of losses caused by gray mold (Botrytis cinerea Persoon) in grapevine (Vitis vinifera Linné, cv. Karaerik) under in vitro and in vivo conditions. B. cinerea isolated from diseased grapevines was identified by 18S rRNA gene sequence analysis. The effects of 2.5, 5, and 10 µL doses of essential oils (EO) on mycelial growth, germ tube elongation, and spore germination were investigated in vitro, and the lesion formation on the leaves was examined in vivo. Compared to the control, both thymol and eugenol suppressed mycelial growth, depending on the dose increase, and caused 100% inhibition at the 10 µL dose, whereas 1,8-cineole had no effect on the same parameter at either dose. Germ tube elongation was 100% inhibited by 5 and 10 µL doses of thymol and eugenol, while the same doses of 1,8-cineole inhibited it by 49% and 85%, respectively. Conidiospore germination was inhibited by 22, 45, and 72% at 2.5, 5, and 10 µL doses of thymol, respectively. Under in vivo conditions, the three EOs inhibited lesion formation on leaves, depending on the concentration increase, and inhibition ended with 100% at their 100 µL dose. In addition, thymol was found to be the most effective EO under in vivo conditions. Our results show that these EOs, which are of biological origin and non-toxic to environmental health, have the potential to be used in the control of gray mold. © 2023, University of Zagreb - Faculty of Agriculture. All rights reserved.