Soybean Rust of Soybean
Published: 03/19/2019
Soybean rust is caused by the fungus Phakopsora pachyrhizi. Symptoms are most common after flowering, beginning on lower leaves. Lesions start to form on lower leaf surfaces as small, gray spots that change to tan or reddish-brown. Lesions are scattered within yellow areas appearing translucent if held up to the sun. Mature lesions contain one to many small pustules, usually on lower leaf surfaces.
The rust pathogen survives in southern states. Movement northward depends on dispersal of spores and disease establishment in new areas, a process that needs to be repeated several times in a growing season for rust to cause an epidemic in northern states. Cool, wet weather or high humidity favor epidemics. Dense canopies provide ideal conditions for disease development.
Foliar fungicides are the only viable option for managing soybean rust and need to be sprayed prior to infection or, at the latest, very soon after initial infection.
Track movement of the pathogen at //sbr.ipmpipe.org to know when to begin scouting.
Symptoms of soybean rust on the leaf surface.
Image: D. Mueller
Leaf underside showing symptoms of soybean rust.
Image: D. Mueller
Patch of soybean plants with soybean rust.
Aerial view of soybean field with patches of soybean rust.
Soybean rust pustules on leaf underside.
Soybean rust begins on the lower leaves in the canopy.
Canopy leaves parted to reveal lower leaves with soybean rust.
Symptoms of soybean rust on soybean leaf.
Soybean rust on soybean leaves.
Leaf underside showing symptoms of soybean rust.
Lesions are scattered within yellow areas that appear translucent if held up to the sun.
Gallery Images: D. Mueller, E. Sikora, A. Robertson, and T. Allen
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.
