INVESTIGATION ON THE DEATH REASON OF ELMS AS WELL AS DISCUSSION ON THE EXISTANCE OF DUTCH ELM DISEASE IN CHINA

Since the 1960's, a lot of elms, Ulmus pumila have been killed in Xing-jiang, Henan, Shanxi, Inner Mongolia and other provinces in China.During 1982-1985, samples of dead elms were collected from a number of plots in plantations and coppice forests. Repeated isolations of the discolored sapwood tissue and bark beetles (Scolytus scheryrewi, S. pygmaeus) as well as the inoculations with these isolated fungi were conducted.The results showed that not only the symptoms on cross sections of the dead elm wood but also the morphology of the fungi were different from those caused by Dutch elm disease.Besides, it is supposed that the major reason for the death was the infestation by the bark beetles and drought was favorable for their reproduction.