Abstract: Taking cherry blossom seedlings as the test material, PAW was used to treat cherry blossom seedlings and their pathogens, and the anti disease effect of PAW on cherry blossom seedlings was studied, in order to provide reference for the application of PAW in the prevention and control of Cerasus crown gall.The results showed that plasma activated water can effectively inhibit the growth of cherry blossom root cancer pathogen Agrobacterium tumefaciens,which could cause damage to the cellular structure of Agrobacterium tumefaciens.The incidence of root nodules of cherry seedlings in the control group was 100%,the average diameter of root nodules was 18.8 mm, the incidence rate of treated seedlings was 56.7%,and the average diameter of root nodules was 8.4 mm.In addition, PAW could increase the expression of PPO,PAL and SOD activities in cherry blossom roots, activating the resistance of cherry blossom plants.In summary, PAW had certain biological control potential and could defend against Cerasus crown gall.