Studies On The Pathogenesis And Disease Control Of The Septobasidium Felts Of Castanea Mollissima

The Septobasidium felts of Castanea mollissima is the main disease of Chinese chestnut in Dabie Moutain in province of Anhui. The Castanea mollissima growth was affected seriously and the Castanea mollissima forest was failed accelerately by the Septobasidium felts. In the thesis, the relationship between the stand condition, nutrients of bark, physiological & biochemical characteristic and the disease resistance to Septobasidium felts of Castanea mollissima were studied in order to find the main factors induced by the disease and control the incidence of this disease. The results will provide evidences to the scientific studies in the future.1. The Septobasidium felts was affected by the varieties and ages of Castanea mollissima, the topography, scales population, the tree canopy, and so on. Among varieties, Zhandiban had ligher resistance with 32.2 infected index, and Qianci-Er-Shuizao was the most susceptible with 88.9 infect index. The infection level of the trees under 4 years was relatively lower, which was 7.8-17.7, and that of the tree of over 13 years old was higher, which was up to 88.9. The infected index of the trees in valley was higher than that on slopeand they were 65.7 and 29.6 respectively. In addition, there was correlation between scales population and disease index. There was remarkable difference among different branches in the Septobasidium felts of Castanea mollissima and there were more Septobasidium felts in the twig branches than on the above branches and side branches of the tree.The canopy was positively related to the disease index and the correlation coefficient was 0.9175.2. The more of the moisture of the bark the lower of the disease incidence by the study of the physiological feature of Castanea mollissima tree. The disease incidence was very higher in the Zhandiban than that of Er-Shuizao and the moisture of the bark was negatively related to the disease index; the research indicated that there was close correlation between the electrical resistance value of diameter at virouse bark in the same tree, and the bark resistance value increased highly along with the height of the tree. The electrical resistance value is higher in the central felt than the other places, so it can be regarded as a feature of the resistance to the disease.3. Lesion expansion, latent period and infection ratio etc. were correlated with some biogenic enzyme such as peroxidase(POD), polyphenoloxidase(PPO), Phenylalanine ammonia-lyase(PAL) were correlated significantly with resistance to host. The activities of POD, PPO and PAL after inoculation Septobasidium Pat. pathogen were studied. The results showed that the activity of these enzyme increased markedly with increse of the time course of infection and the disease expansion, and so on, there was remarkable difference between the new Septobasidium felts and the old ones.4. The correlation analysis of nutrtion in variouse barks was studied. The rusult showed that the elements of N,P,K,B were related positively to the disease index(R~2=0.7882, R~2=0.9175, R~2=0.7457, R~2=0.6524); the susceptable Er-Shuizao and Mi-Fengqiu had obvious higher free sugar than that of the resistent Zhandiban and Dahongpao; the tannin levels in varieties was decreased in barks inoculated with Septobasidium felts The decrement of tannin contents of the resistant varieties was higher than that of the sensitive varieties. It was possible because that the tannin was used to defend the harm coursed by the scale insects; the tannin contents is gradually consumed in this process. The decrement of amino acids of the resistant varieties was obvious higher than that of the sensitive varieties. There was much relationship in special structures and fine character of amino acids.5. 6 different times of control treatment against the Septobasidium felts of Castanea mollissima were test. The effect of different handles had significant difference and tung oil, vaseline, cupric sulphate 50 times, sodium hydroxide 10 times and slop were effective treatments. The five kinds of treatments were suggested to be used for controlling Septobasidium felts of Castanea mollissima. Unified predecessor's research according to this research, the results showed that the effective measures should be taken before the first time arise of the Septobasidium felts of Castanea mollissima, which can reduce latent infection of the Septobasidium felts It could control the disease effectively if comprehensive measures, such as thinning and pruning etc. were taken to prevent the disease at the base of chemical controls.