Rhytidhysteron rufulum

Rhytidhysteron rufulum is an ascomycete fungus belonging to the family Patellariaceae. While it is primarily recognized for its role as a saprobe in forest ecosystems, it acts as a facultative parasite, causing bark cankers and necrotic lesions on various perennial crops and woody ornamental plants, particularly in warmer climates.

The host range of Rhytidhysteron rufulum includes various trees such as citrus, coffee, cocoa, and eucalyptus. The pathogen typically colonizes the bark of stems and branches, often invading through wounds, insect damage, or natural fissures. Once established, the fungus disrupts the vascular integrity of the plant, leading to localized tissue death.

The life cycle is characterized by the formation of apothecia, which appear as small, dark, cup-shaped structures with a distinct reddish or orange interior. These structures release ascospores that are dispersed by wind and rain splashes. High humidity and moderate temperatures are the primary environmental drivers that facilitate the germination and infection process.

The economic impact of this pathogen is significant in susceptible areas, as it causes twig dieback, reduced vigor, and premature decline of the host tree. Chronic infections often lead to extensive bark necrosis and wood decay, which significantly hampers the yield and can lead to the death of major scaffold branches in citrus or coffee plantations.

Management and control strategies emphasize a proactive approach to tree health:

• implementation of strict sanitary pruning to remove and destroy diseased branches;
• application of copper-based fungicides to protect pruning wounds and exposed tissues;
• improving tree vigor through proper fertilization and irrigation management;
• maintaining good plantation hygiene to minimize the buildup of fungal inoculum in the field.