To confirm a diagnosis of Citrus Black Spot, the pathogenic fungus must be isolated in culture. This can be difficult, as culturing of the fruit lesions takes up to 14 days with an efficacy of less than 10%. Diagnosis is also complicated by the morphological similarities of the fungal structures to the non-pathogenic strain Phyllosticta capitalensis (formerly referred to as Guignarida mangiferae).December 2015, DP 5: Phyllosticta citricarpa (McAlpine) Aa on fruit, International Plant Protection Convention, https://www.fao.org/3/ml511en/ml511en.pdf, (May 4, 2023) The two species can be distinguished by molecular testing using PCR.
