Dieback and trunk canker symptoms were observed on centenarian plane trees (Platanus orientalis) in Gezi Park and Dolmabahçe Avenue in İstanbul province of Turkey in August 2015. Reddish‐brown canker lesions covered approximately half of the tree trunk, from roots to top of the trees. The external symptoms were chlorosis, defoliation and dieback, and most of the affected trees were leafless. Three fungal species were isolated from necrotic root and stem tissues and identified as Botryosphaeria parva (Anamorph Neofusicoccum parvum), Neopestalotiopsis clavispora and Diaporthe foeniculina (Anamorph Phomopsis theicola) by morphological characteristics and sequencing of the internal transcribed spacer (ITS) and the β‐tubulin (β‐tub) gene regions. Inoculations on two‐year‐old P. orientalis seedlings demonstrated that all three species were pathogenic, but B. parva caused the largest lesions on stems of plane seedlings. Dual inoculations did not show any synergism in pathogenicity. This paper is the first report of B. parva, N. clavispora and D. foeniculina causing root rot and stem canker of plane trees in Turkey, and probably worldwide.