The inhibitory activity of PGE at different concentrations (0.12,
1.2, and 12 g/l), was evaluated using spore suspensions of B. cinerea,
P. digitatum, and P. expansum. To assess the effect of PGE on the
viability of the pathogens’ conidia, 0.5 ml of conidial suspensions
(2
103 conidia/ml) were transferred to 1.5 ml Eppendorf tubes
containing 0.5 ml of PGE solutions with double concentrations of
extract (2) in order to obtain the above desired
final concentrations
(1). Tubes containing 0.5 ml of citric acid 2% were used as
a control. The obtained mixtures containing approximately
1000 conidia/ml were gently mixed and incubated at 22 C.
After 20 h, tubes were vortexed and 100 ml of conidia suspensions
were transferred and uniformly distributed in Petri dishes
containing PDA amended with ampicillin and streptomycin
sulphate (250 mg/l each). Dishes were incubated at 25 C and
the number of colony forming units (CFU) was recorded after
3–4 days.