# Fungi of the _Trichoderma_ Genus: Future Perspectives of Benefits in Sustainable Agriculture
## 4 Application of _Trichoderma_ Fungi in the Control of Fungal Plant Pathogens
### Mycoparasitism  
According to many researchers, the most effective way to inhibit the development of fungal plant pathogens is the process of mycoparasitism [54; 63; 86]. The mycoparasite recognizes and surrounds another fungus, produces approsergonium, and develops on the host surface. Then, with the help of lytic enzymes and toxic compounds, the antagonist degrades the cell wall of the pathogen and absorbs nutrients [20; 31; 32; 55]. Depending on the method of obtaining food, the mycoparasite may take the form of a biotroph, which extracts the necessary substances from the living tissues of the host, or a necrootroph, which first attacks, kills the cells of the pathogen, and then takes nutrients from dead tissues [86; 87]. According to [PERSON] et al. [32], fungi from the genus _Trichoderma_ are most often classified as necrotrophic mycoparasites.  
Mycoparasitic activity involves a multidirectional mode of action, consisting of the production by the antagonist of proteins responsible for transporting nutrients released from host tissues, substances toxic to pathogens (Table 1), as well as Cell Wall-Degrading Enzymes (CWDEs) [87]. Phytopathogenic cell walls are composed of 90% polysaccharides, such as chitin, glucan, chitosan, mannan, and galactomannan, as well as glycoproteins and proteins. Therefore, the main extracellular enzymes responsible for mycoparasitism include chitinases and \(\beta\)-glucanases, which directly degrade host cell walls [21; 32]. In addition, these microorganisms produce proteases which, on the one hand, control the activity, stability, and secretion of extracellular enzymes by _Trichoderma_ sp. [31], while on the other hand, proteases interfere with enzymes and the integrity of cell membranes of fungal pathogens [86; 88].  
This mechanism shows the great potential of _Trichoderma_ sp. for use in plant production. [PERSON] et al. [89] demonstrated that among 11 _Trichoderma_ isolates, the strain _T. virens_ NBAII inhibited the growth of _S. rolfsii_ mycelium to the greatest extent in biculture (growth inhibition-76.37% on day 6, 87.91% on day 12). Moreover, it was observed that this isolate exhibited the highest chitinase and \(\beta\)-1,3-glucanase activities of 2.13 \(\upmu\)m/mg and 2.67 mM/mg, respectively. Similarly, [PERSON] et al. [90] reported that under in vitro conditions, _T. asperellum_ significantly reduced the development of _F. oxysporum_ (percent of inhibition ranging from 68% to 71%). It was also found that this strain showed the highest chitinase and \(\beta\)-1,3-glucanase activities of 8.7-10.3 pmol/s/mL and 1.4-1.98 nmol/s/mL, respectively. In turn, [PERSON] et al. [91] found that _T. asperellum_, which showed the highest activity of CDWEs enzymes among the tested strains (chitinase-87.5%, protease-52.9%, cellulase-84.8%, \(\beta\)-1,3-glucanase-60.5%), greatly inhibited the development of _F. oxysporum_, both in vitro (inhibition rate-99%) and in a greenhouse experiment with cucumber (disease reduction-71.67%). Moreover, long-term studies by many researchers showed that high antagonism of _Trichoderma_ sp. resulting from the increased production of CDWE enzymes limits the growth of the following pathogens: _Corynespora assiicola_, _Curvularis aeria_[92; 93], _Sclerotinia sclerootinum_[94], _Sclerotinum rolfsii_[89], _Aspergillus niger_, _Fusarium oxysporum_[95; 96], _Colletotrichum gloesporioides_, _Botrytis cinerea_[97; 98], _Aspergillus flavus_, _Aspergillus fumigatus_, _Candida albicans_, _Mucor circinelloides_, _Rhizoctonia solani_[99; 100; 101], _Fusarium graminearum_[68], _Fusarium fujikuroi_, _Fusarium tricintum_, and _Fusarium cantenulum_[102].