Main symptoms

The first symptoms caused by the tomato ( chlorosis virus Tomato chlorosis virus , ToCV) appear on the lower and middle leaves of plants randomly distributed throughout the crop. Thus, a chlorotic mottling, or even irregular chlorotic spots, appear between the veins of the leaflets and gradually spread (Figures 1 to 3). Small reddish to brown necrotic changes are sometimes visible on the leaf blade. Subsequently, the yellowing gradually spreads to the upper leaves. After a few weeks, some plants show fairly sustained interveinal chlorosis, generalized to many leaves (figure 4), the veins of the leaflets remaining dark green and contrasting with the rest of the blade. Plants end up aging prematurely; old leaves thicken, curl and become brittle. They sometimes dry out.

Plants are generally less vigorous than healthy plants. Flowers and fruits do not show symptoms, but the latter see their growth and ripening delayed. The incubation period is 3 to 4 weeks.

Visual identification of this virus is difficult because the symptoms can make one think in particular of an eating disorder. Indeed, several deficiencies can be manifested by interveinal yellowing affecting the lower leaves of the tomato (magnesium, potassium, nitrogen ). In France, it should be remembered that the ( pepino mosaic virus Pepino mosaic virus - PepMV ) also causes chlorosis of the limbus in addition to other symptoms making it possible to differentiate it. The same is true for the tomato ( yellow leaf curl virus Tomato yellow leaf curl virus - TYLCV ), also recently introduced very locally in our country, and for the infectious tomato chlorosis virus ( Tomato infectious chlorosis virus - TICV), with which mixed infections are common in some countries