NATURAL OCCURRENCE OF FUSARIUM MYCOTOXINS IN-FIELD SAMPLES FROM THE 1992 WISCONSIN CORN CROP

Analysis of 98 moldy corn samples collected in Wisconsin between Novem ber 1992 and January 1993 for Fusarium toxins by various immunochemica l assays revealed overall average mycotoxin concentrations of 305.6, 2 37.7, and 904.3 ng/g for type A trichothecenes (TCTCs), deoxynivalenol (DON)-related type B TCTCs (total DON), and zearalenone (ZE), respect ively. A small portion (5.1%) of the samples was found to be contamina ted with high levels (>1 mu g/g) of type A TCTCs and total DON during the whole survey. Over 40% of the samples had 100 to 1,000 ng of total DON per g, while 17% of the samples had the same levels of type A TCT Cs, The analytical data were consistent with those from mycological ex aminations for the samples in which various toxic Fusarium spp., inclu ding F. sporotrichioides, F. pone, and F. graminearum, were found. The samples received in November 1992 had relatively low concentrations o f toxin; the average levels of type A TCTCs and total DON were 9.9 and 79 ng/g, respectively. The toxin concentrations became progressively higher in the samples received in December. The average levels for the type A TCTCs and total DON increased to 920 and 355 ng/g, respectivel y, However, the levels of ZE were higher in the samples collected earl ier, The average levels for samples collected in November and late Dec ember were 1,195 and 242 ng/g, respectively. Analysis of selected samp les by high-performance liquid chromatography monitoring with an enzym e-linked immunosorbent assay revealed that T-2 toxin, HT-2 toxin, diac etoxyscirpenol, neosolaniol, and T-2 tetraol (T-2-4ol) were common in these samples. Statistical analysis revealed a weak correlation betwee n the levels of total type A TCTCs and total DON in the samples (r = 0 .18, P = 0.09), but a strong correlation between the levels of ZE and total type B TCTCs (r = 0.75, P < 0.0001) was found, The mycotoxin lev els of total type A TCTCs, total DON-related type B TCTCs, and ZE in t he cobs (5.2, 3.9, and 21 mu g/g, respectively) were considerably high er than those in the kernels (1.0, 0.5, and 0.5 mu g/g, respectively). The type A toxin levels increased From a range of 14 to 35 ng/g to a range of 110 to 538 ng/g after the moldy corn samples were held at 5 d egrees C for 8 days in the laboratory.