The Panel on Plant Health performed a pest categorisation of Phyllosticta solitaria, the causal agent of blotch of apple, for the EU. The pest is a well‐defined fungal species and methods are available for its detection and identification. P. solitaria is present in Canada and the continental states of the USA. The pest is not known to occur in the EU and is listed in Annex IAI of Directive 2000/29/EC, meaning its introduction into the EU is prohibited. The major cultivated host is Malus domestica (apple), but wild Malus and Crataegus species may also be affected. All hosts and major pathways of entry of the pest into the EU are currently regulated. The disease is favoured by warm, wet weather during the growing season. Host availability and climate matching suggest that P. solitaria could establish in parts of the EU and further spread mainly by human‐assisted means. The pest causes premature defoliation, fruit cracking and rot, and twig and branch cankers. At the beginning of the 20th century, disease incidences of 70–90% on fruit of untreated susceptible apple cultivars had been reported and the disease was considered as a limiting factor in the commercial production of those cultivars. Nowadays, the disease is rare in commercial apple orchards, probably due to regular fungicide sprays against other diseases. The pest introduction in the EU would potentially cause impacts to apple production. The main uncertainties concern the host range, the maximum distance of conidial dispersal by wind‐driven rain, and the magnitude of potential impacts to the EU. P. solitaria meets all the criteria assessed by EFSA for consideration as a potential Union quarantine pest. The criteria for considering P. solitaria as a potential Union regulated non‐quarantine pest are not met, since the pest is not known to occur in the EU.