In this study, Trichoderma harzianum BI was evaluated for its capacity to reduce the incidence and
pathogenicity of the root-knot nematode Meloidogyne javanica on tomato. Culture filtrates of T.
harzianum BI at different concentrations, (standard, 1:1, 1:10, and 1:100) were studied. In vitro studies
revealed that hatching of M. javanica eggs were inhibited by the culture filtrates and this inhibition was
positively correlated with increase in the concentration of culture filtrates. Parasitism of M. javanica
eggs by T. harzianum BI ranged from 21% in control to 84% in antagonistic fungi. T. harzianum BI
reduced nematode damage to tomato in vivo, too. Treatment of the soil with the antagonistic fungi and
salicylic acid clearly improved nematode control when applied jointly or alone. The antagonistic fungi
and salicylic acid were further tested for their ability to induce production of defense related enzymes in
tomato. Earlier and increased activities of soluble peroxidase (SPOX) was observed in T. harzianum BI
and salicylic acid treated tomato inoculated with M. javanica. Thus, the present study shows that in
addition to direct antagonism, induction of defense-related enzymes involved in peroxidase pathway
contributed to enhance resistance against invasion of M. javanica in tomato.