Aspergillus Ear Rot of Corn
Published: 03/19/2019
Aspergillus ear rot is one of the most important diseases of corn. It is caused primarily by the fungus Aspergillus flavus, but a few other Aspergillus species may be involved. Typically, this disease is more common in the southern United States than in other areas. Aspergillus ear rot appears as an olive-green mold on the kernels that may begin at the tip of the ear or be associated with injury from insects, birds, or hail. The fungal spores appear powdery and may disperse like dust when you pull back the husk. These signs are most commonly observed at the tip of the ear, but can be scattered throughout the ear and all the way to the base of the ear.
Aspergillus species produce a mycotoxin called aflatoxin. Aflatoxin affects grain quality and marketability and is primarily a threat to livestock health. Aflatoxin is extremely carcinogenic and most countries (including the United States and Canada) have regulations in place to prevent aflatoxin from entering the human food and livestock feed supply. The aflatoxin, which will accumulate as the fungus spreads in subsequent hot and dry weather. The fungus can infect the ear and produce more aflatoxin after physiological maturity, particularly during periods when rainfall delays harvest. It's important to note that kernels with no visible injury or mold may still contain aflatoxin.
The tip of this ear shows signs of Aspergillus ear rot.
Image: T. Faske
Gray-green, powdery mold indicative of Aspergillus ear rot.
Image: A. Robertson
Aspergillus ear rot disease cycle
The Aspergillus fungus survives in soil or crop residue and infects ears during late silking. Spores are spread by wind and insects and infection takes place through insect wounds or other types of wounds or through the silks. Hot, dry conditions favor infection. Stressed plants (from nutrient deficiencies, drought, or feeding damage from ear-invading insects) are often more susceptible to this disease.
Scouting prior to physiological maturity is important to identify areas with mold problems. These areas should be harvested as soon as possible to prevent further mold development. Harvested grain should be cooled, dried, and cleaned immediately after harvest, and stored apart from grain harvested from healthy fields. Insect management reduces the risk of ear rot infection.
For additional information see the Ear Rots, Using Atoxigenics to Manage Aflatoxin, and Mycotoxin FAQs publications.
Olive-green mold on ear characteristic of Aspergillus ear rot.
Aspergillus ear rot signs can sometimes be scattered across the ear.
Aspergillus ear rot fungal spores appear powdery and grayish-green.
Olive-green mold on ear characteristic of Aspergillus ear rot.
This publication was developed by the Crop Protection Network, a multi-state and international collaboration of university/provincial extension specialists and public/ private professionals that provides unbiased, research-based information to farmers and agricultural personnel. This information in this publication is only a guide, and the authors assume no liability for practices implemented based on this information. Reference to products in this publication is not intended to be an endorsement to the exclusion of others that may be similar. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer.
In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights regulations and policies, the USDA, its Agencies, offices, and employees, and institutions participating in or administering USDA programs are prohibited from discriminating based on race, color, national origin, religion, sex, gender identity (including gender expression), sexual orientation, disability, age, marital status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal or retaliation for prior civil rights activity, in any program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing deadlines vary by program or incident.
Persons with disabilities who require alternative means of communication for program information (e.g., Braille, large print, audiotape, American Sign Language, etc.) should contact the responsible Agency or USDA's TARGET Center at (202) 720-2600 (voice and TTY) or contact USDA through the Federal Relay Service at (800) 877-8339. Additionally, program information may be made available in languages other than English.
To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at How to File a Program Discrimination Complaint and at any USDA office or write a letter addressed to USDA and provide in the letter all of the information requested in the form. To request a copy of the complaint form, call (866) 632-9992. Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov.
USDA is an equal opportunity provider, employer, and lender.
©2024 by the Crop Protection Network. All rights reserved.
