EVALUATION OF Trichoderma harzianum AS A BIOCONTROL AGENT ON Fusarium WILT OF TOMATO GROWN IN EASTERN NEPAL

Abstract

Fusarium wilt acts as a limiting factor for the yield of tomato for which Trichoderma spp. has been evidently used as a biological control agent against the wilt. However, the efficiency of fungi is not well understood. The main purpose of this study was to investigate Trichoderma harzianum isolates towards their contribution to growth of tomato in Eastern Nepal to counteract the effect caused by Fusarium wilt. Investigation of T. harzianum was performed under in vitro and in vivo conditions against the pathogen (Fusarium oxysporum). The most dominant species and causative agent of Fusarium wilt was identified as Fusarium oxysporum. Three native Trichoderma antagonists were isolated from fifteen soil samples of different geographical regions of Eastern Nepal. Under in vitro conditions, the results revealed that Trichoderma harzianum, isolate Th-TJ, was found to inhibit effectively the radial mycelial growth of the pathogen by (57%). Under greenhouse conditions, the application of T. harzianum, Th-TJ exhibited the least disease incidence. Also, tomato plants treated with T. harzianum, Th-TJ isolate showed a significant stimulatory effect on plant height by (78.33 cm) and the dry weight by (3.33 g) of tomato plants, in comparison to untreated control (1.4 g). Therefore, the antagonist T. harzianum, Th-TJ is chosen to be the most promising bio-control agent for F. oxysporum f.sp. lycopersici. On the base of this study, the biocontrol agents of plant diseases might be exploited for sustainable disease management programs to save environmental risk.