Abstract:

42 isolates of Marssonina brunnea collected from different poplars in Jiangsu, Henan, Shandong, Beijing, Shaanxi and Jilin Provinces of China were studied with the morphological markers, characteristics of colony growth culture, pathogenicity and hyphal anastomosis grouping.No significant difference was found on the morphological features of conidia (shape, mean dimension, size and septum location).Morphological features could not be used to study the specialized forms or isolates within the Marssonina brunnea, but could identify the spices of Marssonina brunnea.Five isolates from the poplar or Section Leuce possessed the characteristics of faster colony g rowth, dark reddish conidiosorus production on PDA medium, germinating only one germtube, mostly pathogenic to P. tomentosa and slightly pathogenic to P.×euramericana I-45, P.canadensis, P.cathayana and P.simonii by artificial inoculation in vitro.The thirty-seven isolates from the poplars of Section Aigeiros and Section Tacamahaca, however, had the characteristics of slow ly colony radial growth and yellowish-green conidiosorus production, germinating 1 ~ 5 mostly 2 ~ 3 germtubes, usually pathogenic to P.×euramericana I-45 and P.canadensis, also pathogenic to P.tomentosa, P. cathayana and P.simonii.The test of hyphal anastomosis showed that hyphal anastomosis developed between isolates from the poplar of Section Leuce, and between isolates from poplars of Section Aigeiros and Section Tacamahaca, but could not develop between isolates from the poplars of Section Leuce and isolates from poplars of Section Aigeiros or Section Tacamahaca.The five isolates from the poplar of Section Leuce were placed in one group and the thirty-seven isolates from the poplars of Section Aigeiros and Section Tacamahaca in the other group.These two groups were similar to the two specialized forms reported by Li (1984) and He et Yang (1991).

Key words: Poplar, Marssonina brunnea, Specialized form, Isolate