Climate suitability of the Mediterranean Basin for citrus black spot disease (Phyllosticta citricarpa) based on a generic infection model

Abstract

Citrus black spot (CBS), caused by the fungus Phyllosticta citricarpa, is associated with serious yield and quality losses. The climate suitability of the Mediterranean Basin for CBS development has been long debated. However, CBS has been described in Tunisia. In this study, a generic model was used to simulate potential infections by ascospores and pycnidiospores together with a degree-day model to predict the onset of ascospore release. High-resolution climatic data were retrieved from the ERA5-Land dataset for the citrus-growing regions in the Mediterranean Basin and other locations where CBS is present. In general, the onset of ascospore release was predicted to occur late in spring, but there is no agreement on the adequacy of this empirical model for extrapolation to the Mediterranean Basin. The generic model indicated that infections by ascospores and pycnidiospores would be concentrated mainly in autumn, as well as in spring for pycnidiospores. In contrast to previous studies, the percentage of hours suitable for infection was higher for pycnidiospores than for ascospores. The values obtained with the generic infection model for Tunisia and several CBS-affected locations worldwide were similar to those for other citrus-growing regions in Europe and Northern Africa. These results support previous work indicating that the climate of the Mediterranean Basin is suitable for CBS development.

Risk-based regionalization approach for area-wide management of HLB vectors in the Mediterranean Basin

“…As in Galvañ et al. (2022) , relative humidity (RH) as a percentage was calculated according to Wallace and Hobbs (2006) using air and dew point temperatures as follows:…”

Metabolomics approach to understand molecular mechanisms involved in fungal pathogen–citrus pathosystems

“…The time between infection and the appearance of symptoms can vary from 2 to 5 months, depending on the infected organ and weather conditions. 92 The main symptoms of P. citricarpa infection in citrus include the appearance of various spots on the fruit peel, such as false melanosis, hard, freckle, virulent, lacy, and cracked spots. False melanosis and hard spot symptoms may also occur on the leaves.…”

Geographic distribution, prevalence, and incidence of citrus black spot caused by Phyllosticta citricarpa in Tunisia

“…In 2019, CBS was first reported in Tunisia, on citrus fruit ( C. limon and C. sinensis ) in the governorate of Nabeul (Boughalleb‐M'Hamdi et al., 2020), demonstrating the ability of P. citricarpa to develop in dry ecosystems with Mediterranean‐type climates (Martínez‐Minaya et al., 2018), which puts the Mediterranean citrus industry at risk (Galvañ et al., 2022). However, the extent and impact of CBS in Tunisia have not been documented so far.…”