Soil fungal population in preharvest maize ecosystem in different tillage practices in Argentina

The distribution of the soil borne fungal population in maize non-rhizospheric soil in experimental trials were studied during the harvest seasons 2000/2001 and 2001/2002. The effect of different tillage practices was evaluated. Soil samples were collected from three tillage treatments, conventional tillage, reduced tillage and no tillage, with and without grazing. The distribution of fungal propagules in different treatments was compared. Soil samples were collected from the top soil (3 cm) before planting, in the sprong. No tillage without grazing and reduced tillage with grazing had the highest densities of filamentous fungi (5.71 and 5.85 log, respectively). The mycological survey showed the presence of six genera of filamentous fungi. They were Aspergillus, Fusarium, Penicillium, Trichoderma, Cladosporium, Alternaria. The species identified from genus Aspergillus were A. flavus, A. restrictus, A. candidus, A. parasiticus and other Aspergillus spp. The species identified from genus Penicillium were P. pinophylum, P. citreonigrum, P. implicatum, P. purpurogenum, P. minioluteum, P. waksmanii, P. restrictum, P. rugulosum, P. funiculosum and P. variabile. Species from genus Fusarium were identified as F. verticillioides, F. oxysporum, F. proliferatum and others Fusarium species. The isolation frequency of Aspergillus increased in the no tillage and grazing practices treatments. The data indicate that different agricultural practices impact soil inocula of principal maize toxigenic fungi in the production area. To our knowledge, this is the first report on the effect of tillage management practices on fungal populations in preharvest maize agroecosystem in Argentina.