Mycoparasitism of Trichoderma spp. in biocontrol of fusarial wilt of tomato

摘要

Wilt of tomato caused by Fusarium oxysporum is one of the most serious diseases posing a threat to its cultivation. As such a thorough search was made to evaluate the mycoparasitic potentiality of three species of Trichoderma, T. harzianum, T. viride and T. hamatum towards minimising the effect of the pathogen on ravages of the crop. All the experimental species of Trichoderma were able to produce lytic enzymes, -1,3 glucanase and chitinase efficiently but their activity could be hastened up in the presence of cell wall material of the pathogen where T. harzianum was recorded to be the best in rank. Lysis of mycelium of the pathogen was achieved by treatment with metabolic filtrate of the antagonistic fungi. SEM micrographs correspondingly showed lysis of pathogenic mycelium due to overgrowth and penetration through hyphal pegs and coiling produced by T. harzianum. Application of the antagonistic fungi in the field showed their ability to reduce the incidence of the wilt disease to a reasonable extent where the performance of T. harzianum happened to be superior over the others.