Alfalfa Mosaic of Alfalfa
Alfalfa mosaic is a widespread viral disease caused by the Alfalfa mosaic virus (AMV). Yield losses up to 40% have been reported. The extent of yield loss is influenced by AMV strain, alfalfa cultivar, temperature, and other environmental conditions. Alfalfa plants are an important reservoir of AMV particles for spreading to other host plants. Symptoms can vary due to environmental conditions and virus and host plant genetics, but include leaf yellowing, mottling, and mosaic patterns. Leaves may also be brittle. Additional symptoms include root death, stand decline, and reduced vigor. Infected plants may have no visible symptoms.
Foliar symptoms caused by alfalfa mosaic virus.
Deborah Samac
Foliar symptoms caused by alfalfa mosaic virus in an alfalfa field.
Deborah Samac
AMV overwinters in crowns of infected alfalfa and survives in seed. Many species of aphids are capable of transmitting the virus to new plants, with the pea aphid being especially efficient.
Alfalfa mosaic virus disease cycle in alfalfa
Mimi Broeske, Nutrient and Pest Management Program, University of Madison-Wisconsin
Plant virus-free seed and use alfalfa varieties with aphid resistance to reduce alfalfa mosaic incidence.
Prepared and reviewed by the Alfalfa Pest Management Working Group.
Foliar symptoms caused by alfalfa mosaic virus.
Foliar symptoms caused by alfalfa mosaic virus in an alfalfa field.
Alfalfa leaves with symptoms caused by alfalfa mosaic virus.
Alfalfa leaves with symptoms caused by alfalfa mosaic virus.
Gallery images courtesy Deborah Samac and Craig Grau.
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