Visual Corn Mold Identification 

By Jared Heckart & Tim Johnson

There are approximately 13 fungal genera that are commonly seen on corn kernels, making it easier to identify the species.  Since only one species usually grows on corn kernels at a time the genus is also easy to identify, however there are always exceptions to the rule. Fusarium, Penicillium, and Aspergillus can be difficult to determine exactly which classification they fall under due to the common qualities in each. 

Under certain conditions of temperature, relative humidity, and grain moisture, molds can grow within the kernel and spread during transportation and storage.  Mold causes several issues such as lowering the grain quality, effects on human health, and effects on animal health and reproduction.  Mold has a potential to lower grain quality by affecting the feed efficiency or grain processing characteristics. 

Some grain molds produce mycotoxins that can be toxic to farm animals, wildlife, or humans. A combination of corn that was 20% infected with Penicillin rubrum and 80% clean grain was fed to a pen of 55lb pigs and resulted in their death in less than 32 hours (Christensen, 1969).  The mold needs to be identified, so the producer can determine the best way to deal with the problem.  Once the mold is identified, the producer will be able to take steps in preventing future occurrences of the problem.

Identifying the fungus is important because if the fungus is present throughout, it could tell if the grain or feed is possibly toxic.  Fungi have very limited minimum requirements for growth.  Understanding which fungi are present could tell a lot about the conditions in which it came from.  Identification of these common fungi usually happens with a visual observation of the colony on the kernel.  The important things to look for when identifying the fungi are:

1. Size of the colony
2. Colony texture which includes density, amount, and arrangement of the structures
3. Pigmentation of the mycelium or fruiting structures
4. Colony reverse as seen in the agar.

Identification of Corn Fungi

Word Glossary

Alternaria Alternata

Aspergillus Mold Comparison

Aspergillus Clavatus

Aspergillus Flavus

Aspergillus Fumingatus

Aspergillus Glaucus

Aspergillus Niger

Aspergillus Versicolor

Chaetomium

Cladosporium

Episoccum

Fusarium Moniliforme

Fusarium Graminearum (Gibberella Zeae)

Fusarium Tricinctum

Fusarium Poae

Fusarium Sporotrichioides

Mucor

Nigrospora

Penicillium Brevi-compactum

Penicillium Cyclopium

Penicillium Funiculosum

Penicillium Oxalicum

Rhizopus Stonlonifer

Stenocarpella Maydis

Trichoderma

Key management steps to minimize grain mold and mycotoxin contamination.

1. Ensure proper storage conditions — grain moisture, temperature, relative humidity
2. Minimize mechanical damage — harvest and postharvest shipping and handling
3. Minimize insect damage — pre-harvest and postharvest storage
4. Plant tolerant hybrids — some tolerant hybrids available
5. Sanitation of storage facility — critical management practice
6. Chemical management — propionic acid, mineral oils
7. Assay moldy grain for mycotoxins — Toxicology Lab, Vet Diagnostic Center, UNL
8. Segregate, blend, or destroy contaminated grain — as per FDA regulations

Mold In a Can!!!

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