Sclerotial development of the pathogen was prevented with many Trichoderma isolates or the number of sclerotia formed significantly reduced (Table 2). Maximum inhibition occurred when T. harzianum AS15-1 and T. harzianum AS15-4 were paired with R. solani. With these no sclerotia were produced at all. There was no correlation between the antagonism of isolates in dual culture and their inhibition of sclerotia production in vitro. For example, T. virens AD1-5 was a class 3 (non-antagonist) isolate, but it strongly inhibited sclerotial development.