Management strategies and distribution of Aphanomyces root rot of alfalfa (Medicago sativa), a continuing threat to forage production in the United States |
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| Authors: | Jennifer M Giles Conner L Tordsen Travis R Rebstock Bruna Bucciarelli Deborah A Samac Andrew E Sathoff |
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| Institution: | 1. Department of Biology, Dakota State University, Madison, South Dakota, USA;2. USDA-ARS, Plant Science Research Unit, St Paul, Minnesota, USA;3. USDA-ARS, Plant Science Research Unit, St Paul, Minnesota, USA
Department of Agronomy and Plant Genetics, University of Minnesota, St Paul, Minnesota, USA |
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| 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. |
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| Keywords: | alfalfa Aphanomyces disease management Medicago |
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