Study of Lavandula dentata, Salvia rosmarinus, and Cymbopogon citratus essential oils profile and antifungal activity of their mixture against the gray mold Botrytis cinerea

In this study, we investigated the chemical profile essential oils (EOs) extracted from <i>Cymbopogon citratus</i>, <i>Salvia rosmarinus</i>, and <i>Lavandula dentata</i>, as well as their antifungal activity against <i>Botrytis cinerea in vitro</i> and <i>in vivo</i>. GC-MS analysis showed that the EOs major components of <i>C. citratus</i> EOs were, Geranial (42.91%), Neral (34.11%), and β-Pinene (9.32%). While the <i>S. rosmarinus</i> major EOs components were Camphor (17.60%), α-Pinene (14.39%), and 1,8-cineol (14.13%). Contrariwise <i>L. dentata</i> EOs, Camphor (33.95%), 1,8-cineol (32.35%), and β-Pinene (5.23%) were the predominant compounds. Regarding the <i>in vitro</i> antifungal activity, the EOs of three plants inhibited the mycelial growth of <i>B. cinerea</i> in a dose-dependent manner. Moreover, at the concentration of 0.32 µL/mL air, all EOs demonstrated the inhibition of the mycelia growth of <i>B. cinerea</i>. In addition, the combination of EOs increased the antifungal activity of <i>B. cinerea</i> compared to their individual application. According to simplex-centroid design analysis, the most efficient antifungal of the mixture of EOs extracted from <i>L. dentata</i>, <i>S. rosmarinus</i>, and <i>C. citratus</i> was noted EOs at a ratio (1:1:1). This mixture inhibited the mycelial growth at 1.6 µL/mL, with IC₅₀ and IC₉₀ value of 0.46 µL/mL and 0.81 µL/mL, respectively. In addition, <i>in vivo</i> tests showed that this EOs mixture significantly reduced the decay of cherry tomatoes caused by <i>B. cinerea</i> with an average of 88.37%. Also, the disease severity value recorded for the plant treated with the EOs mixture was 19.29% compared to the control with an average of 88.57%. This study demonstrates that the mixture of <i>L. dentata</i>, <i>S. rosmarinus</i>, and <i>C. citratus</i> EOs is a promising natural antifungal agent for managing <i>B. cinerea</i> infections.