Yield loss from TMV is a result of reduced number, size, and marketability of fruit. The virus may be introduced on contaminated seed, infected crop plants and weeds, and tobacco products. TMV is very persistent and infective. It is spread primarily by humans handling infected plants and mechanically transmitting the virus to healthy plants. Symptoms of the disease are variable and depend on the virus strain present, the tomato variety grown, and temperature.
High temperatures tend to mask foliage symptoms.
Susceptible varieties infected early are stunted and pale green in color. Fruit symptoms are usually absent but may include various forms of uneven ripening. Tobacco Mosaic Virus - severe strains of TMV cause distinctive fruit mottling. Virus-infected plants cannot be cured, therefore, effective management relies on prevention. Resistant varieties, identified by the letters TMV in seed catalogs, on seed packages, or on variety labels should be planted where available.