Abstract: To explore the control mechanism of fermentation broth of Stremptomyces roseoflavus Men-myco-93-63 on cucumber powdery by means of electronic microscopy as well as cytochemical technology, then, Ultrastructure changing of the host cell wall and Sphaerotheca fuliginea(Schlecht.) Poll. was studied. Scanning electron microscopy was employed to investigate the spore germination, growth of mycelium, sporulation time treated by fermentation broth of Men-myco-93-63.The results showed that by means of TEM, being treated with fermentation liquid of Men-myco-93-63 against cucumber powdery mildew, the host cells produced defense structures and material related to infection, it showed that the host cell wall was thickened and deeply stained, solidity of papilla structure produced under the cell wall, dark material deposited between the cell wall and plasmalemma. The number of haustellum of Sphaerotheca fuiginea was reduced obviously, haustoria became malformed and haustorial wall thickened, organelles disintegrated, haustoria necrotizcd finally, the haustoria can't absorb favourably nutrition from the host. By means of scanning electron microscopy which employed hat the fermentation broth of Men-myco-93-63 reduced sphaerotheca fuiginea(Schlecht.) Poll germination 31.51%.The amount of hypha were restrained a certain extent after treatment by the fermentation broth of Men-myco-93-63. The hypha on the host surface had taken place a series of change, such as hypha distortion, clone sparsing and decreesinsing,and which delayed come into being sporule about two days. The control effect on powdery mildew was confirmed by observation with scanning electron microscopy.

Key words: Cucumber powdery mildew, Fermentation liquid of Men-myco-93-63, Resistant mechanism, Ultrastructure, Electron microscopy, Hypha

CLC Number: 

• S436.421