Root Rots of Corn
Published: 03/19/2019
Corn root rots are very common and are caused by several soilborne pathogens such as Pythium, Fusarium, and Rhizoctonia spp. Root rots occur to some extent in every field, causing economic losses under wet conditions. Aboveground symptoms include stunting, uneven growth, chlorosis, small or poorly filled ears, or wilting. In saturated conditions, effects of root rot are difficult to distinguish from the effects of oxygen deficiency and poor root development. Root symptoms are more reliable for diagnosis. Initially, small yellow-brown lesions develop on roots; roots later turn dark brown and are obviously decayed. Fine root decay may not be apparent without careful examination. Fine roots slough off after rotting; their absence is another root rot symptom.
Root rot is generally reduced by standard seed fungicide treatments on corn. Planting corn when soil temperature is above 50°F and soil moisture is not excessive also may reduce risk.
Symptoms of Pythium root rot.
Image: A. Robertson
Rotted roots resulting from Pythium infection.
Image: C. Grau
Corn root discoloration from root rot pathogen infection.
Symptoms of Pythium root rot.
Rotted roots resulting from Pythium infection.
Symptoms of Fusarium root rot.
Corn roots that have been dug up and washed, revealing rot.
Gallery Images: C. Grau, G. Munkvold, K. Wise, G. Shaner, and A. Robertson
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, 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 State or local Agency that administers the program or contact USDA through the Telecommunications Relay Service at 711 (voice and TTY). 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, Mail Stop 9410, Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov.
This work is supported by the Crop Protection and Pest Management Extension Implementation Program from the U.S. Department of Agriculture’s National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.
USDA is an equal opportunity provider, employer, and lender.
©2025 by the Crop Protection Network. All rights reserved.
