Didymella lycopersici is best known for the lesions it causes on the stems and, to a lesser extent, on the fruits of the tomato.

Of cankers with slightly depressed tissues, may occur at various levels of the rod : on its lower part, at the surface or just below (black foot) (Figure 1), in height at the stripping injury and disbudding (Figure 2). They are rather damp and dark brown . The epidermis and cortex gradually break down (Figure 3), and the xylem tissues turn brown . These cankers spread and gradually surround the stem and / or the petioles, thus disrupting the sap currents. Ultimately, it is not surprising to observe the yellowing, wilting and drying out of the leaflets located downstream of the lesions. When a canker has surrounded the crown, the entire plant may die.

Some changes also develop on the fruit , often at the stem scar; these are wet, black , and evolve quite quickly (figure 4). Eventually, large spots with concentric rings cover the fruits. These can gradually mummify or fall . Symptoms on fruits also appear during their conservation and marketing.

On the leaflets , we can observe initially brown and damp spots , especially localized on the periphery of the leaf blade, and evolving rapidly to cover sometimes large sectors (Figures 5 to 7). Brown patterns in more or less concentric arabesques are clearly visible on the injured tissues. These spots, often chlorotic on the periphery, end up necrosis and drying out . Decomposed tissue can fall out. The flowers would also be attacked and destroyed.

On all affected organs, tiny globular structures (distinguishable with the naked eye but more easily with a magnifying glass) (figure 8) and more or less brown to black dot the altered tissues. They are very numerous on the fruits, more sparse on the stems, rare on the leaflets.