Spore Trap, Isolation, And Identification Of Pathogen Of Peach Gummosis

Peach tree gummosis was thought to be associated with physiological disorder caused by pruning, extensive management or stresses. However, the peach gummosis disease which is caused by pathogen gets more and more important with the popular of the disease on many peach orchards. Disease symptoms are always associated with lenticels, wounds, and include gum formation on trunks, scaffold limbs, and braches or necrotic lesions. Species in the genus Botryosphaeria are well-known as pathogens causing canker, blight, dieback and gummosis disease in numerous woody perennial hosts, Botryosphaeria spp. have been overlooked as important causal agents of peach tree gummosis in Hubei Province of China, but the epidemiology of the pathogen is not clear. The work presented in this thesis initiated by the spore trap of the pathogen causing the disease in Hubei Province, by analysis of conidial morphology, cultural characteristics, and nucleotide sequences of three genomic regions of the internal transcribed spacer region. And then, the factors that influence the dispersal of pathogen spore by analysis of the weather data in study area was discussed, and different growth situation on different temperature and pH value condition was also studied in this paper. The results are summarized as follows:1. On the period of March2012to December2013, by the conidial spores of culture characteristics, conidial morphology, pathogenicity, along with phylogenetics analysis of ITS, Lasiodiplodia theobromae were trapped in June24-30,2012; September22-28,2012; October6-12,2013; November4-10,2013. The spores trapped in2012were from the diseased limbs of peach trees while the spores trapped in2013were from the peach prunings.2. By analysis of the weather data in study area, there were at least three continuous days that the daily mean relative humidity was above90%and the mean daily mean temperature was about25℃on the dispersal weeks of L. theobromae conidial spores from he diseased limbs of peach trees; there were at least three continuous days that the daily mean relative humidity was about70%on the dispersal weeks of L. theobromae conidial spores from the peach prunings, but the daily mean temperature was ruleless. 3. The most moderate growth temperature of peach gummosis pathogen L. theobromae was25-30℃, while the most moderate growth temperature of the most prevalent pathogen in Hubei Provence B. dothidea was30℃. The growth of peach gummosis pathogen L. theobromae in the modified Richard solution which the pH value was less than the contrast one was limited while the growth of peach gummosis pathogen L. theobromae in the modified Richard solution which the pH value was more than the contrast one was normal; and the growth of B. dothidea was slower than L. theobromae in contrast solution.