ABSTRACT
Phoma tracheiphila, the causal agent of the citrus disease, mal secco, was investigated for its presence in sampled branches of severely infected trees at two sites in Sicily. We find the fungal pathogen at high probability in natural wounds and at leaf abscission zones. Hail clearly creates wounds through which fungal invasion can occur. We do not find a strong effect of branch orientation to the pathogen presence. Infection sites appear to be at random. We demonstrated a strong correlation between the visual presence of Phoma tracheiphila and outgrowth of the fungus in culture, from samples taken at random from the same visually examined specimens. The relationship of these findings to chemical control is discussed.
