A 4‐Year Study of the Association Between Gibberella Ear Rot Severity and Deoxynivalenol Concentration

To determine the association between visual disease severity and deoxynivalenol (DON) concentration in Fusarium graminearum silk‐inoculated maize ears, 23 Ontario hybrids were assessed in 1989, 1991, 1992, and 1993. The relationship was exponential and consistent between years. Ears with more than 25% of the kernels visibly infected could have very high concentrations of DON. Both temperature and rainfall in July and August influence the level of disease severity and the subsequent DON accumulation. Visual disease severity ratings should be sufficient for the selection of more resistant genotypes in corn improvement programs during routine screenings. Thus, mycotoxin analyses can be reserved for initial selection of parental material and final verification of developed inbreds or hybrids. No relationship was found between hybrid maturity and disease severity or DON concentration.