Storing Harvested Corn and what to Expect from High-Moisture Corn

Harvested grain with fungal growth after a short period of incubation in the laboratory. Similar results can occur in grain storage areas that are not properly maintained.

Over the past month a lot of acres of corn have been harvested.  In some of those cases the corn that was harvested was what could generally be considered high-moisture corn.  Some farmers received a premium by harvesting high moisture corn and taking it straight to the elevator.  However, managing high moisture corn is not easy since corn that goes directly into on-farm storage needs to be quickly dried to less than 15% moisture (24 hours or less).  Drying corn reduces the likelihood of fungal growth on the corn in storage.

Several different fungi can grow on stored grain.  However, not all of the fungi that grow on harvested corn grain are problematic.  Most of the fungi that grow on the corn kernel are obligate saprophytes and simply grow there because there is moisture and a minimal source of food.  But, excess trash in the harvested corn as well as damaged kernels can increase the likelihood of fungi developing in storage since those materials can hold moisture and make it easier for the fungus to grow on that particular substrate.

Corn placed into grain storage at moistures above 15% can begin to grow fungus if heat and air flow are not constant.  In some instances this season electricity that was being used to run driers stopped after grain was placed into storage.  In as little as 24-36 hours, the corn on top developed a green fungal growth.  Remember, once drying and heating are continued after that period the fungus doesn’t disappear.  The fungal spores that produced the green fungus are still present and can begin to grow again if a conducive environment reoccurs.

Aspergillus flavus growing on corn kernels. The light green color, and heavy sporulation as evidenced by the spore mass above the kernels in the petri dish are characteristic of A. flavus. However, not all green fungi growing on corn are A. flavus as several other fungi can produce a green pigment.

Some important pieces of information to consider when initiating grain storage:

-moisture is important to monitor and corn with moisture above 15% should be dried to a moisture below 15% within 24 hours

-fungal growth on harvested grain can develop in extremely short periods of time if the environment within grain storage is conducive for development

-mycotoxins can be produced in the field or in grain storage, especially in grain storage if the harvested grain isn’t handled correctly

-several fungi can grow on corn and are green in color, not all of them produce toxins and if a question arises regarding the specific fungus growing on corn grain please give us a call to collect a sample and determine the fungus present in the laboratory

-if the presence of aflatoxin is suspected there are some places that will conduct analysis to determine the presence and concentration in the harvested grain:

-Bunge North America (http://www.bungenorthamerica.com/locations/index.shtml)

-Mississippi State Chemical Laboratory (http://www.mscl.msstate.edu/)

-Midsouth Grain Inspection Service (901-775-1871)

-don’t store harvested grain in trucks or combines for any period of time following harvest since fungi can grow quickly

-once aflatoxin is present in harvested grain you can’t make the toxin go away; however, cooler temperatures and reducing moisture in the grain can reduce the likelihood of increasing aflatoxin production

Extreme close-up of Aspergillus flavus growing on a corn kernel.

Aspergillus niger is another common fungus that can grow on harvested corn. The black fungal growth is the most common characteristic produced by A. flavus.