Main Symptoms

Significantly different symptoms are observed on plants of different types of tobacco infected with CMV, at times these symptoms remind those caused by TMV (tobacco mosaic virus) (figures 1 to 9):

- more or less severe mosaic patterns, with or without vein banding and / or interveinal yellowing (figure 1 and 2). Some strains responsible for bright yellow to white mosaic, like "Aucuba", or yellow and cross-linked have been reported;
- various anomalies of lamina in shape and appearance, such as the presence of blisters, filiform shape or curling (figure 3 and 4) ;
- localised necrotic lesions (figures 5-8) consisting of small beige to brown etches arranged in rows or rings, mosaics, chlorotic and necrotic lines which sometimes follow the veins of lamina and give it an "oak leaf" appearance. These symptoms are mostly found on the lower leaves and particularly of dark tobacco;
- widespread necrotic lesions cause the destruction of the terminal bud. They are followed by numerous necroses on the leaves, veins, stem and pith. These symptoms, which may affect a large proportion of plants are observed mainly in dark tobacco. They can be confused with those caused by TSWV (tomato spotted wilt virus). Similar symptoms have sometimes been associated with viral infections of combinations such as: TMV + PVY-N  or  TMV + CMV. Necrotic strains of CMV on tobacco have also been reported particularly in the Philippines and France.

Note that foliar lesions may damage cured leaves (figure 9).

Some of these symptoms are confused with those caused by other viruses such as TEV and TMV, AMV and TRSV.

Mixed infections involving CMV and PVY are relatively common in many countries. They are responsible for far more dramatic symptoms, sometimes resulting in lethal necrosis.

Some of the information on the worldwide distribution of the disease is obtained from surveys conducted by CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco). The reliability of the information is not confirmed in all countries.