Late blight (LB) caused by Phytophthora infestans (Mont.) de Bary, is one of the most destructive diseases of potato and tomato worldwide. Globally, application of fungicide is an effective approach for potato LB management. Isolates of P. infestans were collected from different fields in Egypt and characterized using microsatellite markers and mitcondrial DNA. Twelve fungicides were applied in vitro to test their control P. infestans isolates. Nine potato cultivars were evaluated under artificial inoculation. Field trials were conducted to evaluate the efficacy applied fungicides to LB management and potato productivity at El-Behera governorate in two seasons. Our results revealed that collected isolates of P. infestans were A1 mating type, 23_A1 clonal lineage and Ia/IR1 mitcondrial DNA. Furthermore, potato cultivar Burren was highly resistant and recorded the lowest area under disease progress curve (AUDPC). On the other hand, cultivars Alaska, Spunta, Lady Rosita and Mondial were highly susceptible and revealed the highest AUDPC values. In vitro, all fungicide applications inhibited linear growth of P. infestans isolates (EG-Pi1 and EG-Pi2). For field trial, Equation-Pro, and Consonto were the best effective fungicides in respect of LB management where lowest disease severity and AUDPC were recorded in both prophylactically and curatively during two seasons. Moreover, potato tuber production significantly increased with Equation – Pro application. The results of this study provided crucial information for potato breeding programs and crop improvement as well as successful management strategy for late blight challenge.