In 2019, a bleeding canker with a sour-smelling and brownish liquid exudate was observed on mature (>10 years old) black poplar (Populus nigra) trees in eight poplar plantations in the Hamadan, Kermanshah, Isfahan, and Kohgiluyeh and Boyer-Ahmad provinces of Iran. Up to 85% of trees were affected in some stands and the trees showed a general decline and yellowing of leaves. The exudates and cankers were found on the trunk in spring and summer (Fig. 1). The symptoms were similar to bark canker of Populus × euramericanain Spain (Biosca et al., 2006). Samples were collected from symptomatic trees. Fifteen isolations of bacteria were made on nutrient agar (NA; Merck, Germany) from the interface between diseased and healthy tissue based on Moradi-Amirabad et al. (2019). In all cases the predominant bacteria were cream, round, convex and smooth with entire margins on NA. Phenotypic tests were performed based on standard methods (Schaad et al., 2001). All isolates were Gram-negative, and facultatively anaerobic, positive for catalase, nitrate reduction, and hypersensitive reaction on geranium (Pelargonium × hortorum), but negative for oxidase, arginine dihydrolase, urease, lysine and ornithine decarboxylase, hydrogen sulphide and indole production, citrate utilization, and fluorescent pigment production on King's medium B. All isolates produced acid from D-fructose, D-galactose, D-glucose, D-lactose, D-maltose, D-mannitol, D-mannose, D-melibiose, D-ribose, D-sorbitol, D-trehalose, D-xylose, L-arabinose, and salicin. The isolates were phenotypically identical to members of the Yersiniaceae, specifically Rahnellaspp. (Brady et al., 2014). DNA was extracted from a representative isolate (P1) (Moradi‐Amirabad et al., 2019). House-keeping genes gyrB and infB were partially sequenced (Brady et al., 2008) (Genbank Accession Nos. MT107177 and MT107178) and had 100 and 99.67% identity with Rahnella sp. strain L31-1-12, respectively. Using a neighbour-joining clustering algorithm ba
