Fungi and their mycotoxins associated with maize ear rots from emerging maize farms in the Eastern Cape, South Africa

 Maize is South Africa’s most important crop. The Eastern Cape (EC) has been identified as an area of strategic importance for increased production, however, research on diseases affecting production in the province is lacking. This baseline study thus surveyed for ear rots at EC farms and determined the species and mycotoxins present. Diseased maize ears were collected from 11 farms. Fungal isolations were made and strains identified using morphology and DNA sequence comparisons. Translation elongation factor 1- α was sequenced to identify Cladosporium, Fusarium and Stenocarpella strains. LC-MS/MS was used to test for the presence 14 mycotoxins, including aflatoxin B1, aflatoxin B2, aflatoxin G1, deoxynivalenol (DON), diplodiatoxin, 15-acetyl-deoxynivalenol (15-ADON), fumonisin B1 (FUM B1), fumonisin B2 (FUM B2), fumonisin B3 (FUM B3), HT-2, T2 and zearalenone (ZEA). Ninety-three fungal strains were isolated and found to belong to Fusarium (73%), Stenocarpella (19%) and Cladosporium (8%). Mycotoxigenic species detected included Fusarium boothii (DON), F. graminearum (DON and ZEA), F. oxysporum and F. verticillioides (FUM); F. poae, F. subglutinans and F. temperatum (various emerging mycotoxins); and Stenocarpella maydis (diplodiatoxin). Mycotoxin analysis indicated samples were contaminated with DON (58%), diplodiatoxin (58%), 15-ADON (42%) and ZEA (25%). This study found known mycotoxin producers and their associated mycotoxins. Mycotoxins were detected at elevated levels, with 45% of the samples found to be contaminated with multiple mycotoxins. The identification and preservation of the causal agents will allow future work to focus on understanding abiotic and biotic factors that influence mycotoxin production.