Bitter rot

Glomerella cingulata is a fungal pathogen responsible for causing bitter rot, a destructive disease that affects a wide variety of fruit crops globally. It functions as an ascomycete and is widely recognized for its ability to persist in orchards through latent infections, often emerging with full force during the ripening stage of the fruit.

This pathogen impacts a broad spectrum of plants, including apples, pears, mangoes, avocados, citrus trees, and grapes. By attacking fruits, stems, and leaves, Glomerella cingulata disrupts the normal physiological processes of the plant, significantly reducing both fruit quality and overall yield quantity.

Symptoms typically start as small, circular, light-brown spots on the surface of the fruit. As the infection progresses, these spots darken, become sunken, and expand rapidly. A hallmark sign is the appearance of concentric rings of fungal fruiting bodies (acervuli) that produce pinkish or orange spore masses in the center of the decaying tissue.

The development of the disease is heavily dependent on environmental conditions, specifically warm temperatures and high humidity or persistent rainfall. The fungus thrives in moist environments, where spores are spread by water splashes and wind, infecting susceptible tissues through natural openings or small wounds caused by insects or hail.

Managing bitter rot requires a multi-faceted approach to minimize losses:

• Consistent sanitation, including the removal of mummy fruits and dead twigs from trees.
• Pruning trees to improve air circulation and sunlight penetration, which helps keep the foliage dry.
• Applying protective and systemic fungicides during periods of high disease pressure.
• Utilizing pest management programs to reduce mechanical injury to fruits.
• Monitoring orchard health and removing any symptomatic fruit during the season.