Clover yellow mosaic virus - Datasheet

Authors: Hammond, Rosemarie

Submitted to: Center for Agriculture and Biosciences International (CABI) Invasive Species Compendium
Publication Type: Book / Chapter
Publication Acceptance Date: 7/30/2020
Publication Date: 7/30/2020
Citation: Hammond, R. 2020. Clover yellow mosaic virus - Datasheet. Center for Agriculture and Biosciences International (CABI) Invasive Species Compendium. https://doi.org/www.cabi.org/isc/datasheet/14306.

Interpretive Summary: Clover yellow mosaic virus (ClYMV) is a sap-transmissible, plant pathogenic potexvirus, occurring mainly in western North America. It is not known to be vector transmitted. Symptoms on its primary host, clover, include green striping of leaves and stunting of plants. Serious reductions in red and white clover stands have been shown to be due primarily to ClYMV. Although the major host is clover, it can also infect other crops such as peas, faba beans, green beans, cucumber, vetch, and ornamental plant species. It has recently been reported in Florida, England, and the Czech Republic in verbena and was intercepted in a tulip species in the UK. These ornamental species could serve as a potential pathway for spread. The datasheet summarizes geographic distribution, potential risks and routes of infection to new areas, biology and ecology of the pathogen, economic impacts, diagnostic methods, and prevention and control measures. Although ClYMV is not regarded as a quarantine pathogen, the information in the datasheet will be of value to growers of crops known to be susceptible to ClYMV and to quarantine and regulatory officials.

Technical Abstract: Clover yellow mosaic virus (ClYMV) was first reported naturally occurring in Trifolium repens plants in the USA in 1961 and to be extensively distributed in western North America; all legumes tested were found to be susceptible. ClYMV has been reported in the USA, Canada, Russia, North America, Europe and Australia. ClYMV was identified in Florida in ornamental Verbena canadensis in 2005, and the first report of ClYMV in the UK was made when the virus was intercepted twice in ornamental, trailing Verbena spp. Disease symptoms on the main natural host species of red clover plants include stunting with bushy leaves that have a mosaic appearance and yellowed veins, and on white clover plants include yellow or light green leaf striping, stunting, and distortion. ClYMV is a member of the virus family Alphaflexiviridae, genus Potexvirus and is composed of flexuous elongated particles and contains a genomic RNA of 7015 nucleotides encoding six open reading frames. The virus is easily transmissible by mechanical inoculation to members of 3-9 plant families. ClYMV occurs in mixed infections with white clover mosaic virus, another member of the genus Potexvirus. Transmission through mechanical inoculation from pruning tools is a potential pathway for spread; no animal vector is known. It was reported to be seed transmitted at a low rate. ClYMV is not listed as a quarantine pathogen and the disease can be managed by disinfection of contaminated equipment and bench surfaces. Information in the datasheet includes geographic distribution, potential risks and routes of infection to new areas, biology and ecology of the pathogen, economic impacts, diagnostic methods, and prevention and control measures.