act antagonistically against the active oil components or it may
allow better distribution of components through the agar. The
major factors in testing procedures like differences in mycelia
growth, the time of exposure of fungi to the essential oil and also
the use and quantity of an emulsifier greatly affects the results
produced. A standardized method stipulating values for these
variables needs to be produced while also being able to accommodate
for the insoluble and plastic degrading nature of essential
oils. The method utilized in this study that will allow direct comparison
between different essential oils and methods.
Our results indicated that the most resistant fungi were
A. alternate in disk diffusion method and C. sacchari in agar dilution
assay. This may be due to produces more enzymes by these fungi
which catalyzes the oxidation and thus inactivation of the added
oil. Inhibition of the growth of these fungal pathogens may be due
to emulsion which damages the cell wall and cell membrane to
various degrees due to different capacity to penetrate oil into the
chitin based cell walls of fungal hyphae (Grayer & Kokubun, 2001).
So, as reported in this study each method had specific effect on the
individual fungi. In contrast, agar dilution method showed greater
tolerance to the fungi which is used in this research.
Therefore, the sensitivity of the various pathogens may depend
on the morphological and physiological characteristics of the fungus
hyphae. In general, percentages of inhibition depend on the day
of observation, dose and fungus. In this study, E. platyloba essential
oil showed varying antifungal activities against different plant
pathogenic fungus. According to the results, the various concentrations
had different effect on each fungus. In contrast, in all cases
with rising in the concentration of the oil the zones of growth inhibition
increased. Also in all fungi with passing the time, the resistances
were increased. It would also be interesting to study the
effect of essential oil of E. platyloba against other important fungi
for developing new antifungal agents to control serious fungal
diseases in plant. Thus, it can be concluded that the use of essential
oil E. platyloba could be an alternative to synthetic fungicides for
using in agro industries and also to screen and develop such novel
types of selective and natural fungicides in the treatment of many
microbial phytopathogens causing severe destruction to crop,
vegetable and ornamental plants.