Contact antifungal activity of geraniol in vitro

The contact antifungal activity of geraniol against Neopestalotiopsis sp. and C. gloeosporioides was determined following a procedure described in a previous study [7]. Serial two-fold dilution method was applied to assess the MIC₅₀ of geraniol. Drawing from initial trials, the initial solution underwent serial dilution in 30 mL of PDA medium at 45–50°C across various concentrations (1 μl/mL, 0.5 μl/mL, 0.25 μl/mL, 0.125 μl/mL, and 0.0625 μl/mL) to assess its inhibitory effect on Neopestalotiopsis sp. and C. gloeosporioides. The negative control was treated with an equivalent volume of acetone blended with PDA. Ten mL of toxic medium was poured into aseptic Petri dishes. A 5-mm diameter fungal disc of Neopestalotiopsis sp. and C. gloeosporioides was promptly inoculated at the center of each PDA plate. Subsequently, the plates were incubated in darkness at a temperature of 25°C. Following a 5-day incubation period, colony growth diameter was measured with digital calipers. Every test was replicated thrice.