The Research Of The Pathogenic, The Occurrence Law And The Technology Of Prevention Of Galls On Cryptomeria Tianmu Mountains

Tianmu Mountains in ZheJiang Province is a National Nature Reserve, it has a special forest landscape because of the rare huge cryptomeria forest. In recent years, this forest was faced the serious damage by galls, which caused the cryptomeria population show a severe recession and hundreds of cryptomeria died. This damage is not only affect the landscape but also threat the biodiversity of the Reserve. It is reported that the galls of the cryptomeria has been the most important disease of the cryptomeria in the Tianmu Mountains Reserve. The symptoms of the disease is evidently form some galls on the trees. These galls intercept the water and nutriment, which should be transport to the branches of the trees. So it affect the photosynthesis of the trees and cause the trees died finally .In order to control this disease, this paper did a systematic research, investigated the relationship between the disease and the geography and isolated the pathogen of the disease .Besides, we also researched the biological characters of the pathogen and screened out some chemicals ,which have the inhibition effect to the pathogen.May of 2009, we did a systemic census about this disease occurrence at the Tianmu Mountains Reserve. The result suggested the disease happened everywhere and with a 100% disease incidence in four standard place, Can yuan shi, Zhong gu lou, Da shu wang and Xing mao peng. The cryptomeria gall is a host-lead disease, which affected by many biological factors, such as the age, the grow potential and the altitude of the host and so on. Among these conditions, the age of the host is the best important influence factor.In the research about the pathogen, our assay based on the Koch rule to ascertain the pathogen of the cryptomeria gall. Firstly, we isolated a fungus from the galls , then inoculated it to the 3-4 years old healthy seedlings waiting them to occur the symptoms. Finally, we isolated again this fungus from the new formed galls on the seedlings. Therefore, we could determine this fungus is the pathogen to cause the cryptomeria gall. The colony of this isolate is firstly white then to black gray after cultured on PDA. Through the morphological and molecular identification, this fungus was identified as Botrysphaeria dothidea. After the further research, the results of the biological characters showed that this pathogen could survive between 10℃and 38℃,the best suitable temperature is 26℃and the pH is 4 to 5, besides the fungus grows fast in the culture medium ,which the carbon source is fructose and nitrogen source is ammonium sulfate.In the 8 species of fungicide potency assay, fenshi,jingjunzuo manifested the better inhibition effect. Because of the limitation of the experiment condition ,we haven't to carry out the chemical control assay in field. So, we advise to use 300-fold dilution of fenshi,jingjunzuo to do this research in field in the next step.