ABSTRACT
Trichoderma is a genus of asexually reproducing filamentous fungi and widely distributed in the soil, plant
material, decaying vegetation and wood. The antagonistic properties of Trichoderma are based on the activation
of multiple mechanisms. Trichoderma strains act as bio-control agents against fungal phytopathogens either
indirectly or directly. Indirect mechanism comprises competition for nutrients and space, modification of the
environmental conditions, antibiosis and induction of plant defensive mechanisms, however direct mechanism
encompasses mycoparasitism. Some bio-control agents use only one of these strategies but the most successful
bio-control agents like Trichoderma use several of them. These indirect and direct mechanisms may act
coordinately and their importance in the bio-control process depends on the Trichoderma strain, the antagonized
fungus, the crop plant, and the environmental conditions including nutrient availability, pH, temperature and
iron concentration. Activation of each mechanism implies the production of specific compounds and metabolites
such as plant growth factors, pathogenesis related lytic enzymes, siderophores, antibiotics, and carbon and
nitrogen permeases. These metabolites can be either overproduced or combined with appropriate bio-control
strains in order to obtain new formulations for use in more efficient control of plant diseases.