Evaluation of Antagonistic Effect of Trichoderma Harzianum against Fusarium oxysporum causal Agent of White Yam (Dioscorearotundata poir) Tuber Rot

Studies were carried out on biological control using dual culture method to assess the potential of Trichoderma harzianum against Fusarium oxysporum, the causal agent of tuber dry rot disease of white yam in vitro. The rot-causing fungal organism was isolated from rotted yam tubers collected from different storage barns in Zaki-Biam, Benue State of Nigeria. The biological agent (T. harzianum) was introduced at three different times (same time with the pathogen, 2 days before the inoculation of the pathogen and 2days after the inoculation of the pathogen). The experiment was conducted in the Advanced Plant Pathology Laboratory, Federal University of Agriculture, Makurdi, Nigeria. The plates were incubated for 192 hours and measurements of mycelial radial growths were done at 24 hours intervals beginning from 72hour. The result of the in vitro interactions showed that the highest percentage growth inhibition of mycelia of the pathogen (77.99%) was recorded when T. harzianum was introduced two days before the inoculation of F. oxysporum, followed by introduction of T. harzianum same time with F. oxysporum (45.69%) and the least percentage growth inhibition (13.72%) was recorded when the antagonist was introduced two days after inoculation of the pathogen. In all the treatments, T. harzianum was able to significantly (P≤0.05) inhibits the growth of F. oxysporum throughout the period of incubation. T. harzianum was observed to be effective in reducing the mycelial growth of F. oxysporum in culture in all the treatments and therefore showed the potential for biological control of the pathogen. Minimum inhibition concentration recorded showed that the effectiveness levels of T. harzianum were slightly effective to effective across treatments. It is therefore concluded that the antagonistic potentials of T. harzianum could be used as a good biological control agent of yam tuber rot caused by F. oxysporum.

Keywords: Rot; In vitro; T. harzianum; Antagonistic; F. oxysporum; Yam; Inhibition