Erwinia amylovora causes fire blight, a devastating disease of Rosaceae plants. Fire blight leads to high economical losses in the global pome fruit industry every year. It can be reliably controlled by antibiotics (mainly streptomycin). However, alternatives are in demand due to the emergence of resistant strains and regulatory restrictions. Currently, detection of fire blight relies on immunological, culture- or PCR-based methods. Weak points of these methods are the lack of sensitivity, low speed or the inability to discriminate between live and dead bacteria. Owing to their high host specificity, bacteriophages are promising alternatives for both control and detection of bacteria. We have previously isolated and characterized E. amylovora phages and investigated their ability to control bacterial growth. We observed a synergistic effect between L1, a T7-like podovirus, and the myovirus Y2. A depolymerase enzyme encoded by L1 (DpoL1) is responsible for the synergism. DpoL1 is part of the tail fibers and it degrades the exopolysaccharide capsule of E. amyolovora. To enhance biocontrol efficacy of Y2, we introduced a truncated version of the depolymerase gene (dpoL1-C) into the genome. The additional DNA had no adverse effects. Y2::dpoL1-C showed a better control efficacy in vitro than its parental phage and significantly reduced cell numbers of E. amylovora on detached flowers. In addition, Y2 was genetically engineered to create a bioluminescent reporter phage. To do so, a luxAB gene fusion of Vibrio harveyi was introduced into the genome of Y2. Infection of E. amylovora by Y2::luxAB induced the expression of luciferase, which enabled the rapid detection of viable E. amylovora cells by means of light-emission with a detection limit of 3.8 × 10^3 CFU/ml within 50 min.