Pseudomonas corrugata is a bacterium, as the name of the disease suggests (black , pith tomato pith necrosis ), which also affects the pith of the tomato stem. This initially takes on a translucent appearance and a pale brown tint (figure 1), then gradually darkens. It can also hollow out and retract to form several cavities which alternate more or less regularly with parts still intact ((figure 2). In this case, we speak of marrow “in a pile of plates.” Vascular tissues may show a brownish color (Figures 3 and 4) In addition, the apex is often blocked and the young leaves are chlorotic Elongated, irregularly shaped lesions of brown to black color are visible on the surface of the stem (Figure 5 ) and sometimes petioles A proliferation of aerial adventitious roots may also occur (see Other alterations and abnormalities on the stem ).
 

In addition, other bacteria have occasionally been associated with symptoms of altered marrow. We can mention Pectobacterium carotovorum subsp. atrosepticum , P. chrysanthemi , Pseudomonas fluorescens biotype I, P. cichorii , and more recently P. mediterranea .

For further information on this bacterium, you can consult the sheet Pseudomonas corrugata .