Abstract:Monte-Carlo simulation was used for the evaluation of the risk probabilities of invasion of the fire blight disease caused by Erwinia amylovora via imported apple fruits by considering that the proportion of infected fruits varying on the production area and the year.Four beta distributions were established to describe the probability distributions of the proportion of infected fruits for 4 different scenarios, respectively.Pert distributions employed for estimation of the numbers of the imported apple fruits.The estimation of the expected invasion time for four scenarios were 4 702, 3 458, 216 and 105 years, respectively,and the minimal expected time was 14 years in the fourth scenario, in which described there were no phytosanitary requirements for fire blight.The invasion risk increased with the gain of the imported number.