Phoma fruit rot

Paraboeremia putaminum (formerly known as Phoma putaminum) is a fungal pathogen that primarily affects stone fruit crops. It is known to cause fruit rot, leading to significant post-harvest losses and reduced yield quality. The fungus is widespread in regions with high humidity and favorable microclimates for fungal growth.

The disease is characterized by the appearance of dark, sunken lesions on the skin of ripening fruits. As the infection progresses, the spots expand, and small black pycnidia (fruiting bodies) develop within the necrotic tissue. These structures produce spores that are released during humid weather, facilitating the rapid spread of the pathogen across the orchard.

Environmental conditions such as persistent rain, high relative humidity, and moderate temperatures are critical for the development of an outbreak. The fungus survives the winter on plant debris, including mummified fruits left on the ground or within the tree canopy, as well as in bark crevices and pruning wounds.

The impact of this disease is mainly observed in the reduction of marketable fruit yield and quality. Infected fruits lose their firmness, become unsightly, and often drop prematurely. In severe infection cases, the fungus may also colonize young shoots and woody tissues, potentially leading to shoot dieback and structural damage to the tree.

Effective management requires an integrated approach to sanitation and chemical control. Growers are advised to remove and destroy all mummified fruits, as they act as a reservoir for the pathogen. Thinning the canopy improves airflow and reduces humidity around the fruit. Preventive applications of registered fungicides during critical stages of fruit development and following pruning are essential for maintaining a healthy orchard environment.