Abstract: On the basis of the investigation of larch shoot dieback,it was showed that the disease is distributed in 8 provinces (districts) and HO counties (cities),according to the distribution map of epidemic area.No pathogen was discovered on seeds,seedlings,healthy fresh shoots,or branches,trunks,bark and xylem of the larch over two years old.The infected seedlings and shoots are carriers.Under natural condition,the pathogen spores can only be alive for 13 days after it was separated from the host.However,the pathogen within the host tissues can be alive 3~4 years,therefore the seedlings,scions,logs and small diameter logs should be quarantined.The sample inspection and anatomy are major measures for the quarantine,aidded by germination and isolation tests if necessary.To clear up the infected individual seedlings or/and the infected shoots of the log are the simple,easy and effective methods.