Peacock spot

Peacock spot is a devastating fungal disease caused by the pathogen Venturia oleaginea. This fungus is a specialized parasite that primarily colonizes the leaves of olive trees, leading to significant physiological stress and productivity losses if left unmanaged.

The disease affects the European olive (Olea europaea) almost exclusively. While the leaves are the primary target, severe infections can also affect fruit stalks and petioles, which negatively impacts fruit quality and tree vigor over several growing seasons.

The visual symptoms typically appear as circular, dark-colored lesions on the upper leaf surface. Over time, these spots develop a yellow halo around a darker center, resembling the pattern of a peacock's tail feathers. Under conditions of high humidity, a greyish-black layer of fungal spores may become visible on the lesion surface.

Development and spread of Venturia oleaginea are heavily influenced by environmental factors. The fungus thrives in cool, moist weather, with the most active infection cycles occurring during periods of rain and fog. Spores are primarily dispersed by splashing raindrops from infected leaves to healthy parts of the canopy.

Management strategies focus on reducing inoculum and improving tree microclimate:

• Conducting thinning pruning to ensure good airflow within the canopy.
• Applying copper-based fungicides during the rainy spring and autumn months.
• Sanitizing the orchard floor to remove fallen, infected leaf litter.
• Monitoring local weather patterns to time preventative spray applications effectively.