Ear Rots in Corn

by Justin Haerr, Agricultural Systems Management major

Ear rots are fungal diseases that have stressed corn in every locality in which it is grown. Main diseases are Diplodia, Fusarium, Gibberella, and Aspergillus, with the later three producing mycotoxins that are toxic to both humans and livestock. Here in the Eastern Corn Belt, the symptoms of these fungal diseases show up in the ear around the milk stage of corn reproductive growth, or the R4 growth stage, sometime in Mid-August until the corn is harvested. In the cases of the Diplodia, Fusarium, and Gibberella pathogens, they are most viable in wet, humid conditions around the time of silking and around three weeks after silks have emerged as well. In the case of Aspergillus, the opposite holds true as the pathogen favors hot, dry weather at the time of silking up to three weeks after. In many cases, bird and insect damage open pathways for the pathogens to enter the ear and infect the host. These environmental factors play a role in how to plan on scouting for these diseases and also play a big role in how to manage potential fungicide applications, future hybrid selections, crop rotation, etc.

The financial impact is prevalent in yield loss and in some cases poor application of product, but the impact it could have on food security is a true issue. The end product cannot have a large amount of these mycotoxins in them, for they can have an impact on the health of livestock and of humans. Testing for the rots at elevator probes penalize the producers for the poor quality of that grain, and in certain situations, when need be, loads can be rejected from entry into the elevator to keep our food supply safe. In certain years, such as the 2016 crop year with high alfatoxin testing at elevators, the diseases are prevalent in every load. Environmental conditions for the area can impact the local market, and that can be seen in the price for corn at elevators.

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This blog post was an assignment for Societal Issues: Pesticides, Alternatives and the Environment (PLNTPTH 4597). The views expressed are those of the author and do not necessarily reflect the views of the class, Department of Plant Pathology or the instructor.

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