AbstractExtensive plantations of two Euramerican poplar clones, “I‐214” and “I‐45/51” were badly damaged by frost cracks in N. Greece in 1981 and 1985. A bacterial flora consisting of 7 strictly aerobic (Pseudomonadaceae) and 2 facultatively anaerobic strains (Enterobacteriaceae) was regularly isolated from stained heartwood and occasionally from normal sapwood of cracked trees. Mechanical features of wood such as toughness, wood density and solubility in NaOH were not altered. Lignin and α‐cellulose content of wood were not a