survey of internal infection of erwinia amylovora in symptomless mother apple trees

the internal infections of erwinia amylovora have important roles for disease beginning in the spring and dissemination of inoculum through infected vegetative planting material and nursery trees. in this study, we survey internal infection of erwinia amylovora in symptomless commercial apple cultivars in karaj and damavand cities, using optimized diagnostic methods such as plating on semi selective medium, serological and molecular based assays. e. amylovora was not detected in damavand samples but internal infection was detected in symptomless cultivars, red rome, janathan 3, golab-e-kohanz, in karaj. under favorable conditions, the primary infections that remain latent in the plants, start the disease cycle. diagnosis of erwinia amylovora in asymptomatic plant material of orchards and nurseries by certification programs could prevent development of fire blight disease.