Abstract:

Trichoderma harzianum T88 and T.atroviride T95 in dual culture with Cytospora chrysosperma and Dothiorella gregaria were studied. Whether antagonists produced volatile antibiotic which inhibited the growth of pathogens and nonvolatile antibiotics which inhibited the dry weight of mycelium of pathogens were tested. Mycoparasitic activities of Trichoderma spp. were studied against two serious plant pathogens, Cytospora chrysosperma and Dothiorella gregaria by microscopy and scanning electron microscopy (SEM). Macroscopic observations of fungal growth in dual cultures revealed that T.harzianum T88 and T.atroviride T95 made hyphal contact with the pathogen within 3 days after inoculation, leading to the inhibition in pathogen growth. The volatile antibiotic which antagonists produced inhibited the growth of pathogen in varying degrees. The most inhibition rate reached 80.30% under the airtight condition. The non volatile antibiotics inhibited very strong the growth of pathogens. The dry weight of mycelium was evidently less than that of the control. The non volatile antibiotics were not-sensitive to the heating. The microscopy and SEM investigations showed that T.harzianum T88 and T. atroviride T95 appeared to inhibit pathogens by mycoparasitism, with evidence of either parallel and waved growth, or by penetrating hyphal cells of pathogens by forming hooks, haustoria and appressoria like structures which invariably led to hyphal cell cytoplasm concentration and disruption.

Key words: Trichoderma, Popular, Cytospora chrysosperma, Dothiorella gregaria, Antagonism