In 2014, bark cankers were observed on Caucasian alder (Alnus subcordata) trees in Iran. The disease was characterized by a dark watery liquid often exuding from longi-tudinal cankers in the bark of the tree trunks which stained the surface. Symptomatic tissue from A. subcordatawas sampled from a number of sites in the Mazandaran province. Isolations were performed on nutrient agar supplemented with sucrose (SNA) and yielded bacterial colonies that were uniform, round and whitish. The bac-terial strains isolated from alder trees in Iran were similar to Brenneria alnibased on phenotypic and genotypic (nucleotide sequences of the 16S rRNA, and housekeeping genes gyrB, and infB) characteristics. The pathogenicity of the representative strains was determined by inoculating stem pieces of A. subcordata. All tested strains caused longitudinal necrotic lesions 30 days after inoculation and were re-isolated from this tissue. To our knowledge, this is the first report of the occurrence of B. alniin Iran, and on A. subcordataglobally.
