''Squash mosaic virus'' (SqMV) is a

mosaic virus A mosaic virus is any virus that causes infected plant foliage to have a mottled appearance. Such viruses come from a variety of unrelated lineages and consequently there is no taxon that unites all mosaic viruses. All the symptoms of each virus ...

disease common in squash plants and other plants, including melons, of the family

Cucurbitaceae The Cucurbitaceae, also called cucurbits or the gourd family, are a plant family consisting of about 965 species in around 95 genera, of which the most important to humans are: *''Cucurbita'' – squash, pumpkin, zucchini, some gourds *'' Lagen ...

. It occurs worldwide. It is transmitted primarily by beetles, including the

leaf beetle The insects of the beetle family Chrysomelidae are commonly known as leaf beetles, and include over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making up one of the largest and most commonly encountered of all beetle ...

('' Acalymma trivittata''),

spotted cucumber beetle ''Diabrotica undecimpunctata'', the spotted cucumber beetle or southern corn rootworm, is a species of cucumber beetle that is native to North America. The species can be a major agricultural pest insect in North America. Spotted cucumber beetl ...

(''Diabrotica undecimpunctata''), and 28-spotted ladybird beetle ('' Henosepilachna vigintioctopunctata''), as well as some other beetles. Plants are infected by the saliva expelled by the beetles as they feed upon the plant. The beetles acquire the virus by feeding upon an infected plant and can retain the virus in their bodies for up to 20 days. Unlike some other mosaic viruses that infect squashes, SqMV is not spread by

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

s. In melons it can be spread by seeds. The results are dark green mosaic, blistering, vein clearing, yellowing of leaves, and hardening. Symptoms include "pronounced chlorotic mottle, green veinbanding, and distortion of leaves". Fruits of infected plants are also affected, becoming mottled and misshaped. There are two strains of this virus: strain 1 has a greater effect on melons than squash while the opposite is true of strain 2. SqMV affects all cucurbits (family

) and some genera of Hydrophyllaceae, Leguminosae, and

Umbelliferae Apiaceae or Umbelliferae is a family of mostly aromatic flowering plants named after the type genus ''Apium'' and commonly known as the celery, carrot or parsley family, or simply as umbellifers. It is the 16th-largest family of flowering plants ...

, except that most isolates do not affect watermelons. SqMV and

cucumber mosaic virus ''Cucumber mosaic virus'' (CMV) is a plant pathogenic virus in the family ''Bromoviridae''. This virus has a worldwide distribution and a very wide host range, having the reputation of the widest host range of any known plant virus. It can be tra ...

(CMV) are the most common viruses among cucurbits, with CMV being the more common of the two. Kendrick is credited with discovering SqMV in 1934, though McClintock may have discovered it in 1916 when he described a highly similar virus, calling it "cucumber virus".

References

{{Taxonbar, from=Q16992685 Viral plant pathogens and diseases Comoviruses