Moldy grain and vomitoxin levels vary considerably within the grain lot. This is largely because the number of ears infected with Gibberella zeae, the fungus that causes Gibberella ear rot and produces vomitoxin in the grain, and number of infected kernels on a given ear within a field are highly variable. In addition, ears, and kernels with a similar appearance in terms of surface moldiness may have vastly different levels of internal fungal colonization, and consequently, different levels of vomitoxin contamination.