Fabraea leaf spot

Fabraea leaf spot, caused by the fungus Fabraea congener (syn. Diplocarpon mespili), is a significant fungal disease affecting various rosaceous plants. This pathogen is known to cause severe defoliation, which negatively impacts tree vigor, fruit yield, and overall harvest quality in orchards.

The disease primarily targets hosts within the Rosaceae family, including quince, pear, medlar, and hawthorn. In susceptible species, the infection can spread rapidly across the canopy, making the disease a particular concern for commercial fruit production and ornamental nurseries alike.

Symptoms typically manifest as small, circular, reddish-brown to black spots on the foliage. As the infection progresses, these spots expand and coalesce, leading to chlorosis, necrosis, and premature leaf drop. Infected fruits often develop dark, sunken lesions, which significantly degrade their market value and storage potential.

The development and spread of Fabraea congener are highly dependent on moisture and moderate temperatures. Rainfall and overhead irrigation facilitate the dispersal of spores throughout the tree canopy. The pathogen typically overwinters in fallen leaves on the ground, producing fruiting bodies that release spores to initiate new infections in the spring.

Control strategies for Fabraea leaf spot emphasize an integrated approach. Sanitation is critical; removing and destroying infected leaf debris reduces the primary inoculum source for the following season. Fungicide applications, particularly during the early growing season when new leaves are vulnerable, are essential to prevent widespread infection.

• Remove and destroy fallen leaf litter.
• Maintain good canopy airflow through pruning.
• Apply protective fungicides early in the season.
• Monitor trees for early spotting symptoms.