Flyspeck

Flyspeck, caused by the fungus Schizothyrium pomi, is a common fungal disease affecting the surface of pome fruits. Although it is primarily a cosmetic issue that does not degrade the internal quality or flavor of the fruit, it significantly impacts the marketability of the produce, as blemishes lead to downgrading of fruit grades.

This pathogen has a relatively broad host range, primarily infecting apple and pear trees. Furthermore, it has been observed on various citrus varieties and certain ornamental plants, including orchids like Cattleya. Its ability to survive on various substrates makes it a persistent challenge for orchard management.

The visual symptoms are characteristic and easy to identify: small, black, shiny spots resembling fly droppings appear on the fruit skin. These spots are individual fungal structures called apothecia. They are firmly attached to the cuticle and often appear in clusters, creating a dirty appearance that persists throughout the storage and distribution process.

Environmental conditions are the primary drivers for disease development. The fungus thrives in humid environments where relative humidity remains consistently above 90% and temperatures stay between 18°C and 25°C. Poor orchard sanitation and dense, unpruned canopies are the main factors that allow the fungus to proliferate by preventing the rapid drying of fruit surfaces.

Effective control measures require a combination of preventative cultural practices and strategic fungicide applications. Pruning is essential to increase sunlight penetration and air movement within the tree canopy, which reduces the duration of surface wetness. Additionally, implementing a balanced fungicide spray schedule during the summer months is critical for high-value commercial orchards to prevent the establishment of the fungus.