Corn ear rots reduce yield, contaminate grain with mycotoxins and can make harvested corn difficult to market. Infected grain is often discounted or rejected when toxin levels exceed feed or food safety thresholds.
Several corn ear rot species can infect your fields, each with different symptoms, damage and toxins produced.
Where corn ear rot problems start
Most ear rot pathogens survive on crop residue and infect developing ears during silking. That means risk is often tied to field history, residue levels and environmental conditions during pollination. Fields under stress from drought, nutrient deficiencies or insect damage are more vulnerable, as these factors create entry points for infection.
Understanding when and where infections begin helps prioritize scouting efforts and identify high-risk areas before symptoms become widespread.
Why identifying corn ear rot matters
Identifying the type of corn ear rot in your fields will enable you to reduce yield losses, protect grain quality and avoid costly surprises at harvest. Recognizing early signs of infection is key to staying ahead of the problem and reducing mycotoxins in corn.
Many corn ear rots share similar traits and biology, making them difficult to distinguish early in development. Fortunately, there are some symptoms you can watch for to help identify what type of fungal disease is present in your field.
Corn ear rot diseases
Aspergillus ear rot in corn
Aspergillus ear rot appears as olive-green, dusty mold that typically starts at the tip of the ear and can spread across the kernels.¹ It develops under hot, dry conditions, especially in drought-stressed fields or where ears are damaged by insects or hail. It produces aflatoxin, a highly carcinogenic mycotoxin that can render grain unmarketable and pose serious risks to livestock health.²
Diplodia corn ear rot
Diplodia ear rot begins as a white mold at the base of the ear, eventually covering the kernels and producing lightweight, “mummified” ears.³ It often occurs when dry conditions during silking are followed by wet weather, particularly in fields with high residue or continuous corn. While it does not produce mycotoxins in the U.S., it can still reduce grain quality and lead to feed refusal in livestock.⁴
Fusarium ear rot in corn
Fusarium ear rot appears as scattered patches of tan, pink or salmon-colored mold, often with starburst patterns on individual kernels. It commonly develops in ears damaged by insects, with infections occurring across a wide range of environmental conditions. It can produce fumonisin, a mycotoxin that is especially harmful to swine and horses and may lead to grain rejection even when symptoms are limited.⁵
Gibberella ear rot in corn
Gibberella ear rot appears as a pink-to-red mold that typically starts at the tip of the ear and can spread between kernels beneath the husk. It thrives in cool, wet conditions during and after silking, especially in fields with corn or small grain residue.⁶ It produces vomitoxin (DON) and zearalenone, which are tightly regulated and can result in grain being discounted or rejected due to feed safety concerns.⁷
Identifying corn ear rot early is essential to protecting both your yield and grain quality. By recognizing the unique symptoms and risk factors associated with each type, you can take timely action to minimize losses and prevent mycotoxin in corn. Regular scouting, residue management and informed harvest decisions are your most effective tools for managing corn ear rot.
Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent or a seed company professional like your regionalBASF representative.
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Endnotes
- Wise, Kiersten, et al. “An Overview of Ear Rots.” Crop Protection Network, 12 Nov. 2024, https://cropprotectionnetwork.org/publications/an-overview-of-ear-rots.
- Wise. “An Overview of Ear Rots.”
- Wise, Kiersten, et al. “Diplodia Ear Rot of Corn.” University of Kentucky College of Agriculture, Food & Environment Extension Plant Pathology, Plant Pathology Fact Sheet PPFS-AG-C-05, https://plantpathology.ca.uky.edu/files/ppfs-ag-c-05.pdf.
- Paul, Pierce and Anne Dorrance. “Diplodia Ear Rot.” C.O.R.N. Newsletter, vol. 2016, no. 30, Ohio State University Extension, 2016, https://agcrops.osu.edu/newsletter/corn-newsletter/2016-30/diplodia-ear-rot.
- Wise. “An Overview of Ear Rots.”
- Wise. “An Overview of Ear Rots.”
- Willyerd, Katelyn T., Pierce A. Paul, and Peter Thomison. “Gibberella Ear Rot and Mycotoxins in Corn: Sampling, Testing, and Storage.” Agriculture and Natural Resources, Ohio State University Extension, Apr 7, 2016, https://ohioline.osu.edu/factsheet/plpath-cer-04.
