Skip to main content
ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #390321

Research Project: Genetic Improvement and Cropping Systems of Alfalfa for Livestock Utilization, Environmental Protection and Soil Health

Location: Plant Science Research

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

Author
item GILES, JENNIFER - Dakota State University
item TORDSEN, CONNER - Dakota State University
item REBSTOCK, TRAVIS - Dakota State University
item BUCCIARELLI, BRUNA - University Of Minnesota
item Samac, Deborah - Debby
item SATHOFF, ANDREW - Dakota State University

Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2022
Publication Date: 3/29/2022
Citation: Giles, J.M., Tordsen, C.L., Rebstock, T.R., Bucciarelli, B., Samac, D.A., Sathoff, A.E. 2022. Management strategies and distribution of Aphanomyces root rot of alfalfa (Medicago sativa), a continuing threat to forage production in the United States. Plant Pathology. ppa.13563. https://doi.org/10.1111/ppa.13563.
DOI: https://doi.org/10.1111/ppa.13563

Interpretive Summary:

Technical Abstract: Alfalfa (Medicago sativa L.) 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-gray discoloration 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 has 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 non-host plants.