Biological control of phytopathogenic fungi through lytic action of Trichoderma species

The antagonistic effect of Trichoderma reesei and Trichoderma harzianum was studied towards a range of phytopathogenic fungi; Alternia solani, Botrytis fabae, Cladosporium cucumerinum, Fusarium oxysporum, Fusarium tricintum. Coculture of the phytopathogens and Trichodema under laboratory conditions clearly showed dominance of the Trichoderma species. In all cases, Trichoderma overgrew the phytopathogens and subsequently developed a conidial lawn over the surface. In these studies the lytic action of the pathogen was clearly apparent and the inhibition of growth appears directly related to its ability to hydrolyze the cell walls of the tested microorganisms rather than through the inhibitory action of antibiotics or toxins. Proteinase, mannanase, laminarinase and chitinase activities were determined in the extracellular fluid of Trichoderma. Glucose and laminaribiose were detected after the in vitro hydrolysis of the cell walls of the phytopathogens. The data imply that the nature of T. reesei and T. harzianum antagonism is based on mycoparasitism (lysis) and appears to optimalize with contact between the mycelia.