FUSARIUM VERTICILLIOIDES AND F. PROLIFERATUM ASSOCIATED TO SEEDLING BLIGHT IN MAIZE

Fusarium species are responsible of severe ear rot on maize (Zea mays L.). Pink ear rot is caused mainly by F. verticillioides (Saccardo) Niremberg, F. proliferatum (Matsushima) Nirenberg and F. subglutinans (Wollenweber & Reinking), all mycotoxin producers. The most important mycotoxins are fumonisins, largely found in naturally contaminated foods and feeds. The presence of these fungi as endophytes was reported in leaves, stems, roots, grains, but not associated to particular symptoms. Only F. verticillioides is associated to a root and stalk rot in Italy. During routine testing of seed germination of maize samples, using standard methods, the presence of abnormal seedlings, characterized by mesocotyl rot, was observed with an incidence ranging from 4 to 42%. Mycological analysis, conducted on agar medium (PDA), revealed the presence of fast growing colonies with a white-dark violet aerial mycelium on 100% of the samples. Through morphological and molecular techniques, F. verticillioides and F. proliferatum were identified with a frequency of 87% and 13%, respectively. For both fungi Kock’s postulates were verified by artificial inoculation either dipping seeds or seedling roots in a conidial suspension (1 × 106 conidia/ml). Both fungi reproduced the same symptoms. To our knowledge this is the first report confirming seedling blight caused by F. proliferatum on maize seed for the Italian market. In a situation of changing climatic conditions, this may become a relevant pathogen, and neglecting seed transmission could be potentially dangerous, due to severe post-emergence damping off of seedlings.