Archivio Journal of Plant Pathology

Abstract:

Alternaria brassicae and A. brassicicola are the major leaf pathogens on Brassicaceae throughout the world. Here we report a spatio-temporal survey of naturally occurring isolates of these fungi in the Brazilian neotropics. Both fungi were able to induce similar symptoms in common hosts. The fungus A. brassicicola was more frequently isolated (187/322), being prevalent on the Brassica oleracea complex, whereas A. brassicae was prevalent on the B. rapa complex and weed species. Several new hosts and/or new geographical locations of occurrence in Brazil are reported. The presence of host-specificity in A. brassicae isolates was also investigated with cross-inoculation assays. A representative set of Brassicaceae accessions was inoculated with A. brassicae isolates obtained from distinct combinations of host and geographic origin. No host-specificity was observed for all isolates cross-infected all accessions. The present work is the most extensive survey of these fungal species conducted in the neotropics. Comprehensive information about these pathogens will have epidemiological implications, being useful for implementing effective disease management strategies.