Seed-Borne Pathogens of Faba Bean in Egypt: Detection and Pathogencity

Abstract

This study was undertaken to study the seed-borne fungi of faba bean that attack the plants and reduce their yield in Egypt. The results provide a database for further study to control the pathogens. Twenty-six seed samples representing six faba bean cultivars collected from different parts of Egypt were used in this investigation. The blotter and deep-freezing methods were used. Surface- and non-surface-sterilized faba bean seeds were tested to detect and isolate the associated seed-borne fungi. The following 20 fungal species belonging to 13 genera were observed and identified: Aspergillus flavus (Link ex. Gray), Aspergillus niger (Van Tieghem), Aspergillus ochraceus (Wilhelm), Penicillium digitatum (Pers.:Fr.) Sacc., Penicillium italicum (Wehmer), Alternaria alternata (Fr.) Keissler, Botrytis faba (Sardina), Cephalosporium sp., Cladosporium cladosporioides (Frensen. de Vries), Epicoccum nigrum (Link), Fusarium oxysporum (Schlechlendahl), Fusarium semitectum (Berkeley and Ravenel), Fusarium solani (Mart.) Sacc., Fusarium verticillioides (moniliforme) (Sheld), Rhizoctonia solani (Kuhn), Rhizopus stolonifer (Ehr. ex Fr.), Stemphylium globuliferum (Vestergr.) E.G. Simmons), Trichothecium roseum (Pers.) Link, Verticillium dahliae (Ehrenp) Vuill. The blotter method yielded a greater number of fungi than the deep-freezing method on both surface and non-surface sterilized seeds, but the deep-freezing method was better for slow-growing fungi. The pathogenicity test revealed that the most commonly isolated fungi from pre- and post-emergence damping-off and stunted seedlings were F. verticillioides, R. solani, Cephalosporium sp. and V. dahliae. These fungi significantly reduced the photosynthetic pigments in faba bean leaves. Fusarium verticillioides caused the greatest reduction in chlorophyll content (A, B and total chlorophyll). Fusarium oxysporum and V. dahliae significantly reduced carotenoid content. R. solani significantly reduced total phenols content when compared with the other tested fungi.