Their distribution and prevalence varies from year to year but in most years they are present even though it may be at low levels. The most common and important ear mould in Ontario is Gibberella zeae which is the sexual reproductive stage of Fusarium graminearium. This fungus not only infects corn but also small grains such as wheat. Actually, many plant pathologists believe that in years with a high occurrence of Fusarium head blight in wheat, the potential exists for increased Gibberella ear rot in corn. Although, the fungus can produce a white colour mould which makes it difficult to tell apart from Fusarium Ear Rot, the two can be distinguished easily when Gibberella produces it's characteristic red or dark pink colour mould.
Infection begins through the silk channel and thus, infection in most cases starts at the ear tip.
In severe cases most of the ear may be covered with mould growth. Corn silks are most susceptible 2 to 10 days after initiation and this year, the cool and wet weather during this period was ideal for infection. Begin scouting for Gibberella Ear Rot in fields which have a susceptible hybrid planted. If you are not sure how your hybrid rates for Gibberella contact your seed supplier. You should also scout fields with a large number of non-pollinated ear tips or have significant European corn borer or bird damage since this ears are also prone to Gibberella infection.