Diversity Of Pathogens Associated With Moldy Core Of Red Fuji Apple In Shaanxi

Moldy core is an important apple disease. It is the factor that reduces apple fruit quality and quantity, and can be an economically imporptan problem. At present, the studies of pathogens associated with moldy core in different place are inconformit, which lead to the control of moldy core become difficult. So it is necessary to find the relation ship of pathogen and disease which can provide reference for further study.A number of samples were collected from apple producing regions such as Luochuan, Baishui, Liquan, etc. 440 fruit samples and 570 flower samples were collected with or without symptoms.The results were as follows:Survey of incidence of this diease done in Luochuan and Baishui, the date of these two places were 20.0%-36.67% and 7.9%-14.2% respectively and the average rate were 27.78% and 12.39% respectively.Moldy core caused by many kinds of fungi. In this study, 326 isolates were obtained from core region of apple fruit. Morphological characteristics and molecular biology techniques were used for identification. Finally, all these isolates were divided into 20 genuses. But only 10 genuses including 20 species could cause moldy core of apple fruit. These species containing Alternaira arborescens, Alternaira tenuissima, Cladosporium cladosprioides, Cladosporium yanglingliense, Cladosporium tenuissimum, Phoma exigua, Phoma glomerat, Phoma samarorum, Trichothecium roseum, Penicillium expansum, Penicillium italicum, Penicillium commune, Fusarium mali, Fusarium proliferatum, Fusarium tricinctum, Fusarium equiseti Colletotrichum gloeosporioides Sphaeropsis viticola Botryosphaeria obtusa and Epicoccum nigrum. This result indicated that pathogens associated with moldy croe were complicated.In nature, the symptom of moldy core can be divied into three types, including browning (43.22%), moldy (26.10%) and core rot (30.68%).Inoculation experiment showed that Alternaria and Cladosporium were the predominant pathogen of browning. Trichothecium was the predominant pathogen of core rot but often mixed with Fusarium,Penicillium,Phoma and Epicoccum. It was strange that the type of moldy did not occure in this experiment.During different stage of growing, kinds of fungi can be obtained. Such as Alternaria, Cladosporium, Penicillium, Phoma and Epicoccum could be isolated from the flower buding stage to storing stage. But Trichothecium only could be obtained until the flower was withered away. It was indicated that fungicide should be spraied before the blooming and again after flowers gone.In this study, two new methods of inoculation, cutting apple into two pieces and then spraying or injecting spore on the carpel, were found. Compared with other methods used in past, these two methods were more easy and accurate.A new record genus Paraconiothyrium (P. brasiliense) was discovered in Chian and three new species were found: Fusarium mali G.Y. Sun & L.L. Gao, sp. nov. (GL4104); Cladosporium yanglingliense G.Y. Sun & L.L. Gao, sp. nov. (GL09732); P. brown G.Y. Sun & L.L. Gao, sp. nov. (GL09402).