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

Abstract

We 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.

Natural occurrence of mycotoxins in forage maize during crop growth in Japan: case study

“…1). In spite of differences in maturity dates, the pattern was the same in all cultivars, as reported previously (Uegaki et al 2012b). The reason for the rapid increase during ripening in all cultivars might be that the nutritional composition of the ripened grain favours the production of FBs.…”

“…Therefore, reducing them before harvest is more important than reducing them after harvest. But in our previous report (Uegaki et al 2012b), the result was base on only one cultivar. It was not enough knowledge.…”

“…Concentrations of FBs, NIV, DON and ZEA are unlikely to increase during ensiling (Uegaki et al 2012a(Uegaki et al , 2013, but those of FBs can increase during cropping (Uegaki et al 2012b). Therefore, reducing them before harvest is more important than reducing them after harvest.…”

Changes in the concentrations of fumonisin, deoxynivalenol and zearalenone in corn silage during ensilage

“…On the other hand, mycotoxins in corn are known to increase during growing in the field (Warfield & Gilchrist ; Uegaki et al . ). We believe that mycotoxins in corn silage are produced almost exclusively in the pre‐harvest, and mycotoxin production does not occur during ensiling.…”

“…In particular, FUM is known to markedly increase just after the yellow‐ripe stage in the fields (Uegaki et al . ). However, it is unclear whether this increase continues during ensiling during post‐harvest.…”