Abstract:

The pathogen has been examined by Koch's postulates as Alternaria tenuis Nees of red blight of old juniper. It caused a lot of blight needles and tender shoots to die down after artificial inoculation to the seedlings of 2-3 years Sabina chinesis and Platycladus orienta, it was proved that pathogen has very high pathogenicity to the host plants, it also infects some varietis of poplar. Incubation period of the disease is 5-6 days. Some researches on the biological characteritics of the pathogen was also done. The optimum temperature and relative humidity for spores geminetion and hyphae growth are about 25℃ and 90%. The optimum pH value for hyphae growth is 6.Glucose, starch, tryptone. Glutamic acid are good C and N sources in axenic culture of the pathogen.

Key words: Old jumiper, Red blight, Pathogen, Biolobical characteritics