Pre-harvest accumulation of deoxynivalenol in sweet corn ears inoculated with Fusarium graminearum

Three types of commercial sweet corn hybrids [sugary (su1), shrunken or 'su persweet' (sh2) and sugary enhancer (se1)] were silk channel inoculated in 1996 and 1997 with a macroconidial suspension of Fusarium graminearum to de termine how early the mycotoxin deoxynivalenol accumulates in kernels. Dise ase symptoms rapidly developed on all hybrids and were apparent 4 days afte r inoculation. Symptoms stabilized by 28 days after inoculation. Toxin leve ls were greater than 1 mu g/g in kernels as early as 2 weeks after silk eme rgence and rapidly increased to extremely high levels. Susceptibility in al l hybrids decreased as the silk dried out. Deoxynivalenol concentrations we re correlated to disease severity. There was some indication that the sh2 g enotype was more susceptible than the su1 or se1 genotypes. These results s uggest that improvement needs to be made in sweet corn with respect to resi stance to gibberella ear rot.