Studies On Pathogen Identification And Biological Characteristics Of Strawberry Root Rot

Recently, Strawberry root rot ,a kind of soil-brone disease,became more and more serious in the strawberry-planting areas .In this paper,pathogen of strawberry root rot was identified and biological characteristics,pathogenicity,chemical control,enzyme activity were studied.The pathogen of strawberry root rot was isolated from disease tissues. Then inoculated the healthy plant in two means, and found the plant had the same symptom with the speciemen which had gathered from field. Then isolated from the plant again, the fungi were the same pathogen which had been isolated from speciemen. The results showed the pathogenic fungi had strong pathogenicity.The biological characteristics of two fungi were studied in the laboratory. The range of growth temperature of Fusarium oxysporum, Rhizoctonia solani Kuhn were 0~35℃,5~ 35℃respectively, and the optimum was 30℃. The optimum pH of two fungi was 6.26 and 5.35, respectively. Light, different content of nitrogen and carbon in the medium affected on the growth of the two fungi.The results indicated that all fungicides had control effect. But Metalaxyl and Mancozeb were better than Dexon,Chlorothalonil,Iprodione and Prompamocarb on Fusarium oxysporum. To Rhizoctonia solani Kuhn, Dexon,Mancozeb,Metalaxyl and Iprodione were better than Chlorothalonil and Prompamocarb. Therefore, Metalaxyl and Mancozeb were the best fungicides to control strawberry root rot.Strawberry varieties with different resistance were inoculated by Fusarium oxysporum and Rhizoctonia solani Kuhn. The activities of peroxidase(POD), polyphenol oxidase (PPO), phenylalanine ammonialyase(PAL), Catalase(CAT) and Superoxide Dismutase (SOD) were mensurated before and after inoculation. The results showed that there were no relationships between disease resistance and the enzyme activities before inoculation; However,variations of enzyme activities of POD,PPO,PAL,CAT and SOD were closely related to disease resistance of strawberry after inoculation.In resistant variety,the maximum value of SOD content was appeared in 8d after inoculation, the maximum value...