Source: Laura Sweets, University of Missouri

Since the rain from the remnants of Hermine and subsequent rain, many corn fields have taken on a black appearance that is obvious from the road. From a closer perspective, the leaves, stalks and husks appear to be coated with black mold growth. Many of these corn fields had already turned or been turning and the recent spell of wet weather has encouraged the growth of saprophytic or weakly parasitic fungi on the senescing plant tissue giving the fields a black appearance.

It is possible that these sooty molds or secondary fungi could contribute to stalk deterioration or stalk rot. Lodging could become a problem in these fields, especially if there are high winds or strong storms before harvest. These black molds also tend to produce large quantities of spores. It is not uncommon to see dark clouds of spores around combines moving through fields with high levels of black mold or sooty molds. 

Original news release