Biocontrol of Tomato Fusarium wilt by Trichoderma species under in vitro and in vivo conditions

Trichoderma spp. have long been used as biological control agents against plant fungal diseases, but the mechanisms by which the fungi confer protection are not well understood. Our goal in this study was to isolate species of Trichoderma, that exhibit high levels of biocontrol efficacy from natural environments and to investigate the mechanisms by which these strains confer plant protection. In this study, efficacy of the native isolates of Trichoderma species to promote the growth and yield parameters of tomato and to manage Fusarium wilt disease under in vitro and in vivo conditions were investigated. The dominant pathogen, which causes Fusarium wilt of tomato, was isolated and identified as Fusarium oxysporum f. sp. lycopersici (FOL). Twenty eight native Trichoderma antagonists were isolated from healthy tomato rhizosphere soil in different geographical regions of Mazandaran province, Iran. Under in vitro conditions, the results revealed that Trichoderma harzianum, isolate N-8, was found to inhibit effectively the radial mycelial growth of the pathogen (by 68.22%). Under greenhouse conditions, the application of T. harzianum (N-8) exhibited the least disease incidence (by 14.75%). Also, tomato plants treated with T. harzianum (N-8) isolate showed a significant stimulatory effect on plant height (by 70.13 cm) and the dry weight (by 265.42 g) of tomato plants, in comparison to untreated control (54.6 cm and 195.5 g). Therefore, the antagonist T. harzianum (N-8) is chosen to be the most promising bio-control agent for F. oxysporum f. sp. lycopersici. On the base of present study, the biocontrol agents of plant diseases might be exploited for sustainable disease management programs to save environmental risk