Abstract:
Fusarium spp., the causal agent of Fusarium wilt disease, infect sweet pepper inflicting damages
on the roots, stems, leaves, flowers, and fruits. Infection of Fusarium spp. on some crops can be controlled by
using Trichoderma harzianum as a biological control agent. The aims of this study were to determine: 1) the
species of Fusarium infecting sweet pepper; and 2) the in vitro antagonistic potential of T. harzianum in
controlling Fusarium spp. in vitro. The study was conducted from September 2008 to February 2009. Fusarium
spp. were isolated from plant organs showing symptoms of Fusarium wilt; while T. harzianum was isolated from
healthy soil in sweet pepper plantation area. In vitro antagonistic test was carried out using multiple test method
in which Fusarium spp. and T. harzianum were placed in the same antagonistic test space. The percentages of
antagonistic level were determined by measuring the diameter of T. harzianum colony every 24 h during a 7-day
incubation time. The results indicated two species of Fusarium which infected sweet pepper, namely: F.
sambucinum infecting stems, leaves, flowers, and fruits; and F. oxysporum infecting leaves only. The average of
antagonistic percentage of T. harzianum against Fusarium spp. ranged from 71.2% to 94.2%.
