Anthracnose Crown and Stem Rot of Alfalfa
Anthracnose crown and stem rot is primarily caused by Colletotrichum trifolii. This disease can be particularly devastating when it occurs in the crown, as it causes plant death. Lesions typically occur on lower stems and are large oval- or diamond-shaped with a sunken appearance. Lesions are tan with dark borders and may have tiny black acervuli (fungal fruiting bodies) within them. As lesions grow together, stems can die, causing a “shepherd’s crook” appearance of wilted stems. The anthracnose pathogen can spread from stem lesions to the crown in susceptible plants. When this occurs, stems will often die and appear “bleached.” Woody crown tissue will show an internal bluish-black discoloration that spreads throughout the crown in susceptible plants, resulting in plant death. “Summer decline” results from anthracnose infection of susceptible cultivars.
Anthracnose crown and stem rot stem lesions.
Craig Grau
Shepherd's crook symptoms indicative of anthracnose crown and stem rot.
Deborah Samac
Warm, wet weather favors pathogen infection and subsequent disease development. C. trifolii can survive on crop residue and within infected crowns.
Anthracnose crown and stem rot disease cycle in alfalfa.
Mimi Broeske, Nutrient and Pest Management Program, University of Madison-Wisconsin
Resistant alfalfa cultivars are available and should be used where anthracnose is a problem. Practice harvest-equipment sanitation to mitigate field to field pathogen spread. Mow younger, non-infected stands first.
Prepared and reviewed by the Alfalfa Pest Management Working Group.
Shepherd's crook symptoms indicative of anthracnose crown and stem rot.
Anthracnose crown and stem rot stem lesions.
Anthracnose crown and stem rot stem lesions on alfalfa. Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org.
Anthracnose crown and stem rot crown rot phase.
Anthracnose crown and stem rot wilting.
Alfalfa field with anthracnose crown and stem rot.
Gallery images courtesy Deborah Samac, Craig Grau, and Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org.
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.
