Antifungal efficacy and phytochemical characterization of citronella (Cymbopogon winterianus Jowitt ex Bor) essential oil against fungal pathogens causing severe diseases in Mentha arvensis L.

Mentha arvensis L. (family Lamiaceae) is one of the important medicinal plants and India is the largest producer of Mentha oil in the world, contributing about 80% of the total global production followed by China (9%), Brazil (7%) and the USA (4%). However, this crop suffers quantitative and qualitative losses due to the wilt and leaf spot diseases caused by the fungi Fusarium oxysporum and Alternaria alternata, respectively; therefore, an attempt has been made for the management of these fungal pathogens. The citronella essential oil was extracted by hydro-distillation method (Clevenger, 1928). The oil thus extracted was used for in vitro antifungal efficacy against the both fungi F. oxysporum and A. alternata, using poison food technique. The results showed that the minimum inhibitory concentration (MIC) of the citronella oil against F. oxysporum and A. alternata was 1.0 mu L/mL; however, it was cidal in nature at 1.2 mu L /mL and 1.5 mu L/mL against both fungi, respectively. Further, phytochemical characterization of citronella oil was done using GC/GC-MS. Gas chromatographic analysis of the citronella oil revealed 18 phytoconstituents which were identified by retention indices aided with NIST-MS database. The major constituents of essential oil were citronellal (28.78%), geraniol (26.31%), citronellol (12.90%), geranial (9.85%), and neral (7.9%). The findings of the current study show that citronella oil could be an alternative to synthetic fungicides, after detailed investigations.