Identification of mycotoxin‐producing Fusarium spp. isolated from corn and the changes in concentration of fumonisin during the cultivation period

Abstract

AbstractWe estimated the prevalence of mycotoxin‐producing Fusarium fungi and the levels of fumonisin in corn (maize; Zea mays L.) grown and harvested in Tochigi, Japan, in 2009. Fusarium fujikuroi was the species most frequently isolated from ear samples collected after the yellow‐ripe stage, and these isolates produced fumonisin in incubation tests on corn grain medium. Other Fusarium species were also isolated. The concentration of fumonisin in corn grown in the field increased abruptly after the dough‐ripe stage and kept increasing until the full‐ripe stage. The mean concentrations of fumonisin B1 and B2 each exceeded 2000 μg kg–1 fresh matter at the full‐ripe stage, and almost all of the fumonisin was found in ears. Fungi capable of producing fumonisin were consistently isolated from ears sampled after the dough‐ripe stage; we conclude that these fungi produced fumonisin in ears. Although fumonisin‐producing fungi were isolated also from stems and leaves after the dough‐ripe stage, concentrations of fumonisin in these tissues were very low and did not increase over time. It appears that fumonisin‐producing fungi such as F. fujikuroi, F. incarnatum and F. verticillioides were present in the plants from the dough‐ripe stage to full‐ripe stage and the conditions for fumonisin production became more favorable in ears as the plants matured.