Identification Of Pathogen And Screening Of Effective Agents For Bacterial Fruit Rot In Melon

Melon is one of the most important vegetables in our province.It has a long history of cultivation,a wide area and a high economic value.However,with the development of cultivation technology and the improvement of agricultural technology,the increase of melon planting area also makes the occurrence of disease more serious.The occurrence of diseases varies greatly from region to region.In this study,field disease investigation was carried out in the melon planting area of huainan,anhui province in 2017,and diseases with typical fruit decay symptoms were suspected to have occurred on the surface of white melon fruits.The occurrence of this disease seriously damaged the yield of melon,causing economic damage to melon farmers.In order to look for the causative agent of melon fruit rot,this paper carried out the identification of the causative agent of melon fruit rot,the indoor screening of conventional agents and the determination of pathogenicity of pathogens to different melon varieties,thus providing theoretical basis for the epidemic prediction and effective prevention and treatment of sweet melon fruit rot.The results of this study are as follows:(1)Representative field diseased fruits were collected from huainan melon planting area,and bacteria were isolated from the diseased tissue of melon fruit by plate dilution separation method,and bacterial colonies with similar morphological characteristics were obtained.Three representative bacteria were selected for physiological and biochemical tests,sequence analysis of 16S rRNA and gyrB genes,and pathogenicity determination on melon fruit,and the pathogen causing the disease was confirmed to be Bacillus pumilus.(2)Seven kinds of bacterial fungicides were selected from the market to determine virulence and minimum inhibitory concentration of sweet melon and fruit rot.The results showed that the bacteriostatic effects of Copper(succinate+glutarate+adipate)?bordeaux solution and zhongshengmycin on the pathogen were better,but the bacteriostatic effects of Kasugamycin and copper hydroxide were worse.When the concentration of agricultural streptomycin and thiediazole copper copper was 240 mg/L,the growth of bacteria could not be effectively inhibited,which indicated that the bacteria had developed significant resistance to these two fungicides.Copper(succinate+glutarate+adipate)of fatty acid has a good inhibitory effect on short and bacillus.The EC50 was 4.7950 mg/L and the minimum inhibitory concentration was in the range of 6-10 mg/L.(3)The resistance of different melons varieties to inoculation at seedling stage was tested.The results showed that among the 28 melon varieties tested,there were 11 varieties of neutral-resistance(MR)material,5 varieties of neutral-sensitivity(MS)material,3 varieties of susceptible(S)material and 9 varieties of immune(?)material.The results could provide a theoretical basis for the prevention and control of bacterial fruit rot and breeding of resistant melon varieties.