Isolation, Identification and Characterization of Phyllosticta citricarpa Causing Citrus Black Spot Disease in Benin

Citrus black spot is a major constraint to citrus production in Benin. Identification of the pathogen causing citrus black spot disease was carried out in the laboratory on symptomatic fruits. Fruit samples were collected from orchards in 4 citrus-growing agro-ecological zones. A total of 66 representative isolates of Phyllosticta sp. were obtained from isolation. Molecular analysis using PCR of the nucleotide sequences of the ITS regions with universal primers ITS1/ITS4 and specific primers GcF1/GcR and the phylogenetic tree showed that the sequences of all isolates obtained in the different agroecological zones were identical to those of Phyllosticta citricarpa. The pathogenicity test satisfied Koch's postulates by re-isolation of Phyllosticta citricarpa from inoculated fruits. A thorough study of genetic diversity and a full understanding of the behavior of P. citricarpa will pave the way for more targeted approaches to the prevention, control and sustainable management of citrus black spot disease in Benin.