In the in vitro interactions between T. harzianum and
R. solani, the compounds previously isolated during the
saprophytic growth of the antagonists were detected. This
pathogen was used as model in dual-plate confrontation
assays, as it was the most sensitive in the antibiosis assays(Table 3). The detection of T22 azaphilone, as the most
abundant antibiotic produced by the T22 strain, could be
reasonably related to its biocontrol activity. The
T39butenolide is an oxidized form of harzianolide, a
compound not detected during the antagonistic interaction
of this fungus with R. solani.