Fabraea leaf spot

Systematic position and pathogen type: Fabraea maculata (synonym Diplocarpon mespili) is an ascomycete fungus belonging to the order Helotiales. It is a specialized necrotrophic pathogen that affects the leaf tissue, petioles, and fruits of various species within the Rosaceae family.

Host plants and symptoms: The fungus primarily infects quince (Cydonia oblonga), pear (Pyrus communis), and medlar. The disease typically manifests as dark, irregular spots on the upper leaf surface, which can lead to extensive chlorosis, necrotic tissues, and eventually premature defoliation of the trees.

Biology and life cycle: The pathogen overwinters primarily as mycelium or stroma within fallen, infected leaves. In the spring, when temperatures rise and humidity increases, apothecia develop and release ascospores into the air. These spores are dispersed by wind and splashing rain, initiating primary infections on developing foliage.

Environmental conditions and impact: Disease outbreaks are strongly correlated with wet and mild weather conditions. Fabraea maculata requires free water on the leaf surface for spore germination. High humidity and moderate temperatures (approximately 15–22°C) significantly accelerate the secondary infection cycle via conidia, leading to severe yield losses and tree weakening.

Control and management measures: Effective management relies on a combination of cultural practices and chemical interventions. Sanitation is critical: raking and destroying all fallen leaves removes the primary inoculum source. In commercial orchards, a preventive spray program with copper-based fungicides or modern systemic fungicides (such as triazoles or strobilurins) is necessary to protect trees during the growing season.