Yellow fairy cup

The yellow fairy cup (Latin: Calycina claroflava) is a species of fungus in the family Helotiaceae. While traditionally classified as a saprotrophic fungus that decomposes dead organic matter, in an agricultural context, its presence on living trees indicates significant decay or previous damage, suggesting that the host plant is under stress and suffering from wood degradation.

The causative agent develops by producing small, bright yellow, disc-shaped apothecia on the substrate. The mycelium penetrates deep into the wood, secreting enzymes that break down lignin and cellulose. This enzymatic activity undermines the structural integrity of the plant tissues, eventually leading to branch rot and making the tree susceptible to opportunistic pathogens.

The host range includes various deciduous tree and shrub species. In orchards, the fungus is frequently encountered on decaying or improperly pruned branches. If a plant's defenses are compromised by pests or drought, Calycina claroflava can colonize damaged areas, accelerating the deterioration of the wood and potentially spreading if sanitary conditions are not met.

Symptoms of infection are easily identified by the sudden appearance of vibrant yellow clusters on the surface of tree bark or rotting wood. As the fungus matures, the area around the fruiting bodies may show signs of soft rot or tissue necrosis. High humidity and poor air circulation within the tree canopy are the most critical factors promoting the spread of the fungal spores.

To mitigate the risk and protect orchard health, growers should implement the following measures:

• Remove all dead, damaged, or diseased wood through consistent pruning.
• Apply protective coatings, such as wound dressings or fungicides, to any significant cuts on the tree limbs.
• Maintain proper tree vigor through balanced fertilization and hydration to improve natural resistance against fungal colonizers.