Causal Agent: Cucumber Mosaic Virus (CMV).
Several Strains have been reported.
Vector: Aphids (Aphis gossypii, Myzus
persicae and many others.
Distribution: Worldwide.
Symptoms:
Symptoms of this disease very greatly depending on the virus strains
involved. Often the virus causes stunting of the plant giving it a
bushy appearance. Leaf symptoms may vary from a mild, green mottling
to a chlorosis or severe necrosis, or a severe “shoestring”
symptom in which the leaf blades are greatly reduced with only the
central rib of the leaflet remaining. Shoestring symptoms are similar
to the severe symptoms observed with ToMV infection, however, with
the shoestring symptoms the blade of the leaflet is usually more suppressed.
Fruit are reduced in size and often misshapen.
Conditions for Disease Development:
This virus has a wide host range (800 species) from which it can be
acquired by aphids and transmitted in a non-persistent manner. CMV
is mainly a problem where infected alternative hosts survive year
round, as well as in greenhouses where once introduced it can readily
spread from plant to plant by aphids. CMV can also be mechanically
transmitted, however, because it is an unstable virus the chances
of transmission by greenhose workers and their tools is much less
than with a virus like ToMV.
Control:
In greenhouse crops controlling the aphids can greatly reduce
the incidence of this disease. The elimination of weeds and ornamental
plants that harbor the virus, as well as rouging of infected plants,
can reduce the spread of this virus and hence disease incidence.
