Peanut stunt virus (PSV) is a plant pathogenic virus in the family Bromoviridae. It is a member of the genus Cucumovirus. The members of this genus are positive-stranded RNA viruses with a multipartite genome (3-4 parts). The virus particles have an isometric or spherical shape. Distribution and host range PSV was first named as a new disease of groundnuts or peanuts ( Arachis hypogaea ) in 1966. Disease symptoms on the above ground parts of the peanut plants were described as severe dwarfing or stunting – hence the name Peanut stunt virus. Fruit production was also severely reduced. Virginia peanut fields, where this disease was first observed in 1964, had yield reductions of 10-50%. Severe stunting of peanuts had also been observed in North Carolina in 1964. The peanut disease in N. Carolina was reported to be caused by the PSV in 1967. The later report also stated that this virus caused disease in bean (Phaseolus vulgaris) and in white clover (Trifolium repens). After its first description, PSV was quickly diagnosed in beans in Washington State, white clover in South Carolina, peanuts, beans and white clover in Georgia, peanuts in Alabama, and white clover in Florida. Strains of PSV have now been identified in Africa (Morocco), Europe (France, Poland, Russia, and Spain) and Asia (India, Japan, Korea and China ) as well as in the United States. PSV is an economically important pathogen of plants in the family Leguminosae. In addition to beans, peanuts, and clover (7 different species of Trifolium), PSV has been reported to naturally infect peas (Pisum sativum), soybeans (Glycine max), alfalfa (Medicago sativa) and lupine (Lupinus luteus). In 2002, PSV was reported to infect rhizoma or perennial peanut (Arachis glabrata) in N. Florida and S. Georgia. Host range studies have shown that fourteen other plant families can be infected with this virus including agriculturally important crops in the plant families Cucurbitaceae (squash, cucumber, watermelon) and Solanceae (tomatoes, peppers, tobacco). Cultivated Tobacco (Nicotiana tabacum) and celery (Apium graveolens) have also been reported to be naturally infected. Transmission PSV is transmitted from plant to plant by several species of aphids (Aphis craccivora, A. spiraecola and Myzus persicae) in a stylet-borne manner. It can also be transmitted by mechanical inoculation. It has been shown to be transmitted by seeds in peanuts at a very low level but this is not considered to be very important to the spread of