{"id":33652,"date":"2023-07-11T16:30:55","date_gmt":"2023-07-11T16:30:55","guid":{"rendered":"https:\/\/agsci.colostate.edu\/agbio\/?post_type=ipm-pests&p=33652"},"modified":"2026-02-23T23:52:15","modified_gmt":"2026-02-23T23:52:15","slug":"alfalfa-mosaic-virus-amv","status":"publish","type":"ipm-pests","link":"https:\/\/agsci.colostate.edu\/agbio\/ipm-pests\/alfalfa-mosaic-virus-amv\/","title":{"rendered":"Alfalfa mosaic virus (AMV)"},"content":{"rendered":"

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Alfalfa mosaic virus (AMV) in peppers<\/h1>\n

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Overview and disease transmission<\/h2>\n

Alfalfa mosaic virus is an RNA virus that only infects plants and requires living plant cells to replicate. Transmission occurs primarily by aphids, although it is also possible for AMV to be transmitted mechanically (e.g., use of tools that\u00a0came in contact with\u00a0infected plants) as well as through seed.\u00a0Alfalfa mosaic virus is a non-persistently transmitted virus, meaning that aphids can\u00a0acquire\u00a0the virus within minutes of feeding from an infected host and quickly spread it to uninfected plants. Aphids need to only poke or probe plant tissue with their mouthparts to infect a\u00a0host,\u00a0and prolonged feeding is not\u00a0required.<\/span>\u00a0<\/span><\/p>\n

The main reservoir for AMV in Colorado is alfalfa (<\/span>Medicago sativa<\/span><\/i>\u00a0L.), and infection risk is highest for pepper plants\u00a0adjacent to\u00a0alfalfa fields. In our\u00a0field\u00a0research and observations thus far, alfalfa harvest triggers aphids to move to neighboring and adjacent crops, such as peppers, allowing transmission of the virus. Alfalfa mosaic virus overwinters in alfalfa or is propagated the next season through seed transmission, although seed transmission rate is\u00a0relatively low.<\/span>\u00a0<\/span><\/p>\n

[\/et_pb_text][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/07\/AMV-pepper.jpg” alt=”AMV symptoms on pepper” _builder_version=”4.27.5″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” custom_padding=”4%|4%|4%|4%|true|true” border_width_all=”4px” border_color_all=”#F15625″ global_colors_info=”{}”]<\/p>\n

Alfalfa mosaic virus on pepper. This virus is spread by aphids and has become common on pepper in Colorado. Image credit: Taylor Janecek, Colorado State University<\/em><\/p>\n

[\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/07\/Fruit-discoloration-AMV.jpg” alt=”fruit discoloration AMV” _builder_version=”4.23.3″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” global_colors_info=”{}”]<\/p>\n

Example of fruit discoloration from AMV. Image credit: Taylor Janecek, Colorado State University<\/em><\/p>\n

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Examples of<\/span>\u00a0<\/span>leaf vein deformation (left)<\/span>\u00a0<\/span>and\u00a0<\/span><\/span>leaf discoloration (right) on AMV-infected peppers.\u00a0<\/span><\/span>Image credit: Lara Amiri-Kazaz, Colorado State University<\/em><\/p>\n

[\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2026\/02\/3.-Mosaic-chlorosis-on-amv-peppers.jpg” alt=”Mosaic chlorosis on leaves of a pepper plant due to AMV” _builder_version=”4.27.5″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” global_colors_info=”{}”]<\/p>\n

Examples of mosaic chlorosis (blotchy yellowing) on AMV- infected peppers.<\/span><\/span>\u00a0Image credit: Lara Amiri-Kazaz, Colorado State University<\/em><\/p>\n

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