Rhizoctonia Seedling Blight and Root Rot of Soybean
Published: 03/19/2019
Rhizoctonia seedling blight and root rot is caused by the fungus Rhizoctonia solani. Pre- and postemergence damping off can occur. Infected seedlings have reddish-brown lesions on the hypocotyls at the soil line. These lesions are sunken and remain firm and dry. The root rot phase may persist into late vegetative to early reproductive growth stages. Symptoms may disappear if infected plants grow out of the root rot problems, although plants may remain stunted.
Hypocotyl lesions from Rhizoctonia infection.
Image: D. Mueller
Damping off caused by Rhizoctonia seedling blight and root rot.
Image: M. Chilvers
The fungus survives on plant residue or in soils as sclerotia. Infection may occur soon after seed is planted. Cool, wet springs followed by hot, dry conditions are conducive to disease. Disease is more severe on light and sandy soils, and can be more common on the slopes of fields. Unfortunately, many strains of Rhizoctonia can infect corn, alfalfa, dry bean, and some cereal crops, negating the effectiveness of crop rotation.
Eliminating stress factors, such as use of herbicides that cause injury to soybean roots, can help reduce root rot problems. Fungicide seed treatments are effective against Rhizoctonia.
Damping off caused by Rhizoctonia seedling blight and root rot.
Rhizoctonia infected soybean plants (right) compared to a healthy plant (left).
Sunken, dry lesions near the soil line characteristic of Rhizocotonia seedling blight and root rot.
Sunken, dry lesions near the soil line characteristic of Rhizocotonia seedling blight and root rot.
Hypocotyl lesions from Rhizoctonia infection.
Rhizoctonia seedling blight and root rot symptoms include pre- and post-emergence damping off.
Rhizoctonia lesions are sunken and remain firm and dry.
Gallery Images: D. Mueller, A. Robertson, C. Bradley, T. Mueller, and M. Chilvers
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.
