Study On Classification And Disease Diversity Of Root Parasitic Nematodes Of Platycodon Grandiforum

From 2019 to 2022,In order to clarify the species of parasitic nematodes on Platycodon grandiflorum root and the occurrence of diseases,and better control Platycodon grandiflorum diseases.The diseases of soil and plants around the roots of Platycodon grandiflorum in 13 cities of 8 provinces in China were investigated and samples were collected.235 soil samples were isolated.The molecular biological identification method of morphological identification was used to classify and identify the parasitic nematodes of Platycodon grandiflorum root,identify the pathogens of Platycodon grandiflorum disease,and study the diversity of diseases,The results are as follows:1.Our study cleared that there were 21 main types of plant parasitic nematodes in tomato roots in different regions in China:Meloidogyne incognita、Filenchus vulgaris、Tylenchorhynchus crassicaudatus、Tylenchorhynchus cylindricus、Pratylenchus coffeae、Pratylenchus mulchamdi 、 Tylenchulus semipenetrans 、 Helicotylenchus dihystera 、Helicotylenchus martini 、 Helicotylenchus agricola 、 Helicotylenchus reynosus 、Helicotylenchus erythrinae、Helicotylenchus sacchart、Helicotylenchus pseudorobustus、Rotylenchus caudaphasmidius、Rotylenchus phaliurus、Criconemella informis、Aphelenchus isomerus 、 Aphelenchus eremitus 、 Aphelenchus sparsus 、 Aphelenchoides helicus.M.incognita and Caenorhabditis elegans are the main pathogenic nematodes,and Caenorhabditis elegans are more common,which are found in soil samples in different regions of China.The molecular identification and specificity detection of M.incognita were carried out.The results showed that the root knot nematode obtained in this experiment is M.incognita.2.The occurrence and pathogen types of Platycodon grandiflorum disease were clarified.In order to determine the occurrence and types of Platycodon grandiflorum diseases,disease investigations were carried out in the main planting areas of Anhui,Hebei,Henan,Inner Mongolia Autonomous Region and Liaoning from 2019 to 2022.There are 7diseases found.Through observation of field symptoms,colony characteristics,morphological identification,molecular identification and pathogenicity determination,the pathogens of the 7 diseases are Fusarium oxysporum、Rhizotonia solani、Colletotrichum truncatum、Stemphylium platycodontis 、Fusarium equiseti、 Septoria platycodonis and Cuscuta japonica.Platycodon grandiflorum diseases are not evenly distributed in different regions,among which Liaoning diseases are the most abundant.Fusarium oxysporum and Rhizotonia solani of Platycodon grandiflorum are the most widely distributed and the most serious.They have a great impact on the product quality and yield of Platycodon grandiflorum,and cause huge economic losses at the same time.Fusarium oxysporum of Platycodon grandiflorum occurred in Anhui Province,Henan Province,Hebei Province,Liaoning Province and other places,and the disease plant rate was as high as 89.6%;The incidence of Rhizotonia solani of Platycodon grandiflorum in Anhui Province and Hebei Province is as high as 65.6% and 78%.This study identified the species and common pathogens of Platycodon grandiflorum root parasitic nematodes all over China,as well as the regional distribution diversity of different diseases,so as to provide a theoretical basis for the field diagnosis and correct control of Platycodon grandiflorum disease.