A modified assay technique using discs of banana leaves was employed to test the inhibition of
Colletotrichum musae by yeasts, filamentous fungi and bacteria isolated from the surface of
banana fruits. Infection was reduced only when the pathogen was applied to the leaf surface after
the antagonist was allowed to establish itself for at least 48 h. Yeasts that showed no antagonism
in vitro were effective as antagonists in vivo. This assay technique enables rapid screening of a
large number of isolates on leaf tissues and is easier to use than fruits. The interaction of the
pathogen and antagonist was observed on the leaf surface under the Scanning Electron Microscope.
No form of physical inhibition, hyphal degradation or agglutination of spores was
observed. Also, the infection process of the pathogen within the leaf was studied ultrasttucturally.
The pathogen caused necrosis of young banana leaves and ultrastructural changes in the infected
host were similar to those previously observed with other species of Colletotrichum infecting their
respective hosts. 0