The soil-borne fungal species associated with Cephalosporium maydis, as the causal agent of late wilt of corn at the Iberian Peninsula, were identified by monitoring 19 fields showing wilt symptoms in the major crop areas between 2011 and 2012. In 47% of the fields, C. maydis was not identified, but Fusarium graminearum, F. verticillioides, F. equiseti, F. proliferatum, Macrophomina phaseolina, Rhizoctonia solani and Trichoderma harzianum were found to infect corn plants. In the remaining fields, besides C. maydis, other soil-borne fungi were identified at considerable percentages: F. verticillioides (19%), F. proliferatum (19%), F.equiseti (9%), F. oxysporum (9%) and Pythium oligandrum (9%). The vascular growth of C. maydis and other fungal species in corn plants was confirmed by means of analyses with plants showing wilt from three different fields. Both C. maydis and F. graminearum, F. equiseti, F. proliferatum and T. harzianum were isolated at the insertion between the root and the stem and at 10cm height on the stem of plants. The effect of infection by C. maydis on corn plant production was quantified in pots under semi-natural conditions in 2011. In inoculated plants, there was a 54% reduction in the weight of cobs, in addition to a reduction in the weight of roots and shoot (leaves and stem) which were significantly smaller compared to the non-inoculated control; this suggests the great economic impact that late wilt may have under natural conditions. Similarly, this study highlights the complexity degree of the etiology of late wilt, which should be studied by confirming the pathogenesis of the soil-borne fungi identified in the corn with the aim of determining the role of each species on the development of the disease and/or the severity of symptoms.
Etiology; Fusarium graminearum Schwabe; Fusarium proliferatum (Matsush.) Nirenberg ex Gerlach & Nirenberg; Fusarium verticillioides (Sacc.) Nirenberg; soil-borne fungi
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