Management strategies and distribution of Aphanomyces root rot of alfalfa (Medicago sativa), a continuing threat to forage production in the United States

Jennifer M. Giles, Conner L. Tordsen, Travis R. Rebstock, Bruna Bucciarelli, Deborah A Samac, Andrew E. Sathoff

Research output: Contribution to journalArticlepeer-review

Abstract

Alfalfa (Medicago sativa) is one of several legumes that is affected by Aphanomyces root rot (ARR) caused by Aphanomyces euteiches. Symptoms of ARR on alfalfa seedlings include a yellow-grey discolouration of roots, rotting and loss of lateral roots, stunted growth, chlorotic foliage and reduction of nitrogen-producing nodules on roots. Infection can also occur on adult plants leading to loss of lateral roots and nodules. At the seedling stage, ARR decreases alfalfa stand establishment, and field longevity is reduced when adult plants are infected. A. euteiches is an oomycete pathogen that has motile zoospores and thick-walled oospores that can survive for many years in soil. Two races are currently recognized by pathogenicity on differential alfalfa check cultivars. Most alfalfa cultivars contain race 1 resistance, but there is an increasing development of cultivars with resistance to race 2. Management strategies include planting resistant cultivars, avoiding planting in fields with poor drainage and rotating crops with nonhost plants.

Original languageEnglish (US)
Pages (from-to)1231-1240
Number of pages10
JournalPlant Pathology
Volume71
Issue number6
DOIs
StatePublished - Aug 2022

Bibliographical note

Funding Information:
The authors would like to thank Brooklyn Goosen for her graphic design work on Figures 3 and 6 . Mention of any trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. USDA is an equal opportunity provider and employer. This work was supported by Mustang Seeds and South Dakota EPSCoR RII Track‐1 (OAI‐1849206).

Publisher Copyright:
© 2022 The Authors. Plant Pathology published by John Wiley & Sons Ltd on behalf of British Society for Plant Pathology.

Keywords

  • Aphanomyces
  • Medicago
  • alfalfa
  • disease management

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