The plants affected are often very strong and have thick stems . Their apex no longer develops and reveals curled, more or less chlorotic leaflets, wilting at the hottest times of the day (Figures 1 and 2).

Of wet beaches , colored dark brown to black , are seen along the rod , and sometimes spine (Figures 3 to 5). They affect the epidermis and can extend over several tens of centimeters, or even completely cover the stem. Aerial adventitious roots tend to form on portions of stems affected by black pith. A slight mucous discharge is sometimes observed from the leaf scars.

Transverse or longitudinal cuts in the stem show that the marrow is affected (Figures 6 to 8); it presents different facies according to the climatic conditions and the degree of evolution of the symptoms. It can be more or less brown and necrotic , dry and slightly decomposed. Sometimes it stays white and firm in the center; In contrast, the tissues located near the xylem vessels take on a yellowish to pale brown tint and become necrotic. The vessels themselves can turn brown and eventually necrosis. In some extreme cases, the marrow is more or less disaggregated, showing limited transverse cavities or complete collapse of the browned tissue. Alterations can also be observed in the petioles, it would occur in the taproot and some roots.

The disease would start at the base of the stem, especially when harvesting approached, and gradually rise in the plant. Some particularly diseased plants can die. When the climatic conditions become mild again and the plants are slightly affected, the disease regresses. The distribution of diseased plants seems to fluctuate depending on the type of crop: rather distributed randomly in the field, they have been observed in foci in certain shelters.

P. corrugata could cause rots fruit . In addition, black pith symptoms were occasionally observed on young plants in nurseries located in Italy, causing significant damage.