Candelaria

Candelaria is a biological condition affecting woody plants, characterized by the growth of lichenized fungi of the genus Candelaria on the bark of trees and shrubs. While often perceived as harmless epiphytes, in high concentrations, they exert a detrimental effect on the host plant by restricting gas exchange and harboring secondary pests.

The causative agents are fungi within the Candelariaceae family. These organisms create symbiotic associations that allow them to colonize surfaces that are otherwise difficult for other species to inhabit. By firmly attaching to the bark, they can disrupt the structural integrity of the outer layers over time, creating a micro-environment that holds moisture excessively.

The host range primarily includes pome fruits, stone fruits, and various ornamental trees. It is most commonly found in older, neglected orchards where the bark is rough and provides ample crevices for spores to germinate and establish long-term colonies.

Symptoms are easily identifiable by the presence of brilliant yellow or golden-yellow crustose thalli on the trunk and primary branches. The affected areas may show signs of premature bark hardening and cracking, which, if left untreated, provides a breeding ground for wood-boring insects and pathogenic bacteria.

Development is favored by high relative humidity, stagnant air within the canopy, and low light penetration. Prevention is critical and focuses on maintaining the overall vitality of the tree. A well-managed orchard with proper pruning and nutrition is significantly more resistant to the establishment of such lichenized growth.

• Scraping and brushing affected bark areas.
• Applying lime wash to trunks during the dormant season.
• Pruning for better air circulation and light exposure.
• Maintaining balanced soil fertility for plant vigor.
• Using appropriate fungicides as a last resort for severe cases.