Control of crown rot-causing fungal pathogens of banana by inorganic salts and a surfactant

Abstract

Crown rot, a disease complex caused by various fungi, is an economically significant postharvest disease in bananas. Control of banana crown rot-causing fungal pathogens, such as Lasiodiplodia theobromae, Colletotrichum musae, Thielaviopsis paradoxa, and Fusarium verticillioides by inorganic salts, as well as a surfactant, was evaluated. The conidial germination of pathogens was totally inhibited for 2 d at 4 g l-1 of Na2CO3, 5 g l-1 of NaClO, NaHCO3, CaCl2, and 6 g l-1 of NaCl. The same concentrations of salts completely controlled the conidial germination of all pathogens for 7 d with the amelioration of surfactant. This study elucidated how the surfactant enhanced the protective value of the salt to suppress the conidial germination of the pathogens. However, control of the mycelial growth of the pathogens required a higher dosage of salt. Some inorganic salts were not effective in controlling the mycelial growth of the pathogens, although they were ameliorated by the surfactant. The effective treatments to control crown rot of bananas were 5 g l-1 of NaClO, NaHCO3, and 5 g l-1 CaCl2+surfactant. Some salts, when ameliorated with surfactant, had a phytotoxic effect on banana fruits.