In vitro studies on the effect of methanol and dimethyl sulfoxide on the growth and sporification of Penicillium expansum and Botritis cinerea.

Penicillium expansum and B.cinerea are among the pathogens most frequently affecting apples and grapes respectively after harvest. We studied the behaviour of theses moulds when subjected to different concentrations of methanol (MeOH) and dimethyl sulfoxide (DMSO) as a possible alternative method to fungicides in controlling postharvest decay of horticultural products. The experiments were performed with 5 cm Petri dishes containing PDA amended with 0, 5, 10, 20, 30, 40 or 50 L/mL of each of the two tested chemicals. Freshly prepared conidia (50 conidia/plate in 50 L) of P.expansum and B. cinerea were sown onto the media and then kept into an incubation chamber at 21 °C up to 6 and 3 days, respectively. daily, the formed colonies (cfu), the colony diameter and the degree of sporification was monitored. Additionally, Scanning Electron Microscopy (SEM) observations were performed in order to shed light on the effect of these chemicals on P. expansum and B. cinerea growth. Compared to the control, both chemicals affected the growth rate of the two pathogens. The cfu value of P. expansum and B. cinerea was not inhibited significantly but the colony diameter and the degree of sporification decreased as concentration was raised. B. cinerea cultured on DMSO showed a significant drop of sporification up to the tested concentration of 10 L/mL, and a complete inhibition of cfu when the concentrations was higher than 20 L/mL. SEM observations evidenced changes in the pathogen growth behaviour and structure. The importance to fasten or inhibit the sporification will be discussed and data of preliminary in vivo experiments will be presented.