Antifungal activity of monoterpenoids against postharvest pathogens Botrytis cinerea and Monilinia fructicola

Twenty two naturally occurring monoterpenoid compounds were selected for an tifungal evaluation against two of the most common postharvest pathogens on temperate fruits, Botrytis cinerea and Monilinia fructicola. Experiments w ere carried out in order to examine the separate effects of these compounds on spore germination and mycelial growth. The growth inhibition test was c onducted by incorporating the compounds into the medium, or by exposing the fungi to the vapor of the monoterpenoids. The results showed that carvacro l and thymol, the only two phenolic monoterpenoids, were the most potent in hibitors to the two pathogens in the germination and growth inhibition test s. Both of the compounds completely prevented the spore germination and myc elial growth of B. cinerea and M. fructicola at 100 mu g/mL. Even at 10 mu g/mL medium (0.25 mg/petri dish) in the volatility test, carvacrol and thym ol had 85% and 82% inhibition at 48 h against B, cinerea, and 38% and 57% a gainst M. fructicola, respectively. Other monoterpenoids such as eugenol, c itronellol, geraniol, citral, (-)-perillaldehyde, citronellal, (-)-perillyl alcohol and (-)-menthol were good growth inhibitors (by contact) although their activities toward the two pathogens were slightly different, with hig her inhibition found against the M. fructicola.