Characterization of fungal pathogens occurring in potting mixtures and organic fertilizers in Oman

Potting mixtures, which are imported from overseas, as well as local and imported organic fertilizers are commonly used by growers in Oman for vegetable production. However, there is a lack of information about pathogens that might be introduced into farms along with potting mixtures and organic fertilizers. The purpose of this study was therefore to investigate the most common fungal pathogens introduced into farms in Oman via potting mixtures and organic fertilizers. Forty eight samples of potting mixtures and organic fertilizer samples were screened for their contamination with fungal pathogens using different methods. Fungal pathogens were identified using morphological characteristics and sequences of the internal transcribed spacer region of the ribosomal DNA (ITS rDNA). Penicillium, Rhizopus, Aspergillus, Helminthosporium, Alternaria, Trichoderma, Acrospira, Fusarium spp., and three human fungi were isolated from potting mixtures and organic fertilizers. Investigating sensitivity of different Fusarium species to hymexazole revealed high variation among isolates. Three isolates showed resistance to this fungicide. This appears to be the first report of occurrence resistance to hymexazole fungicide among Fusarium spp.