In recent years Acidovorax avenae subsp. avenae was identified as a major cause of bacterial etiolation and decline (BED) in turfgrasses and has become a growing economical concern for the turfgrass industry. The symptoms of BED resemble those of bakanae, or foolish seedling disease, of rice (Oryzae sativa) in which the gibberellins produced by the infecting fungus Fusarium fujikuroi contributes to the symptom development. Additionally, an operon coding for the enzymes necessary for bacterial gibberellin production was recently characterized in plant pathogenic bacteria belonging of the y-proteobacteria. We therefore investigated the possibility for the presence of this gibberellin operon in A. avenae subsp. avenae. A homolog of the operon has been identified in two turfgrass-infecting A. avenae subsp. avenae phylogenetic groups, but not in closely related phylogenetic groups or strains infecting other plants. Moreover, even within these two phylogenetic groups the operon presence is not uniform. For that reason, the functionality of the operon was examined in one strain of each turfgrass-infecting phylogenetic group (A. avenae subsp. avenae strains KL3 and MD5). All nine operon genes were functionally characterized through heterologous expression in E. coli and enzymatic activities were analyzed by LC-MS/MS and GC-MS. All enzymes were functional in both investigated strains, thus demonstrating the ability of phytopathogenic β-proteobacteria to produce biologically active GA4. This additional gibberellin produced by A. avenae subsp. avenae could disrupt phytohormonal balance and be a leading factor contributing to the pathogenicity on turf grasses.