Effects of Organic Acids and Salts on the Development of Penicillium italicum: The Causal Agent of Citrus Blue Mold

Control of Citrus blue mold, caused by Penicillium italicum, has been accomplished by postharvest application of synthetic fungicides. However, the development of resistant fungal strains and increasing public concern over food safety and the environment are driving a search for alternative disease control strategies. In vitro trials were conducted to evaluate the effect of several organic acid and salt compounds on mycelial growth, sporulation, spore germination and germ tube elongation of Penicillium italicum. Among 28 tested compounds, sodium carbonate, ammonium carbonate, copper sulfate, EDTA and sodium metabisulfite completely inhibited mycelial growth and sporulation of Penicillium italicum at only 0.02 M. The lowest Minimum Inhibitory Concentration (MIC), Minimum Fungicidal Concentration (MFC) and EC50 values were recorded in sodium metabisulfite treatment. All tested compounds, except Nicotinic acid, strongly inhibited spore germination and germ tube elongation in a dose-dependent manner. Results from this study provide an important basis for further study into the uses of salt compounds for the control of blue mold of Citrus fruit under semi-commercial conditions.