Abstract
The aim of our work was to study the effect of acibenzolar-S-methyl (ASM) and Rahnella aquatilis (Ra39) on fire blight disease of apple, caused by Erwinia amylovora. Under greenhouse conditions, application of Rahnella aquatilis (Ra39) resulted in disease suppression on the highly susceptible 'M26' rootstock. Application of ASM and Ra39 led to decrease of the disease by 82 and 58%, respectively; and this was correlated with a reduction of pathogen growth within host plants up to 64 and 49.5%, respectively. Further studies in the field under artificial infection condition during full bloom, application of ASM and Rahnella aquatilis (Ra39) on the cultivar 'Gala' resulted in control of the disease for up to 21 and 29%, respectively.