Peach scab

Venturia carpophilia (commonly known as the pathogen responsible for peach scab) is an ascomycete fungus within the order Venturiales. As a specialized phytopathogen, it primarily infects stone fruit trees, significantly impacting both fruit quality and tree health. Understanding its biological nature is essential for effective orchard management and long-term disease control.

This pathogen specifically targets members of the Prunus genus, including peaches, nectarines, apricots, and almonds. The infection is characterized by the appearance of dark, olive-green to black spots on fruit surfaces. As the disease progresses, these lesions may merge, causing the fruit skin to crack and distort, which dramatically reduces its market value and makes it highly susceptible to secondary rots.

The life cycle of Venturia carpophilia involves both sexual and asexual stages. The fungus overwinters as mycelium in lesions on twigs and branches or within fallen leaves. In the spring, when temperatures rise and rainfall becomes frequent, the fungus produces spores that are dispersed by wind and splashing rain onto new vegetative growth, initiating the primary infection cycle.

Environmental conditions play a decisive role in the spread of the pathogen. High relative humidity and prolonged periods of wet weather are critical for spore germination and colonization of host tissues. Dense canopy structures and poor air circulation within the orchard create a conducive environment for the fungus to multiply rapidly through secondary infections occurring throughout the growing season.

Management of peach scab requires an integrated approach to reduce the inoculum load and protect vulnerable plant parts. Key strategies include:

• Rigorous pruning to remove infected twigs and ensure good canopy aeration.
• Sanitation practices, such as removing fallen leaves and mummified fruits from the orchard floor.
• Application of protective fungicides during the pre-bloom and fruit-set stages.
• Choosing disease-resistant cultivars when establishing new orchard blocks.