In Vitro Antagonistic Potential of Trichoderma harzianum for Biological Control of Fusarium moniliforme Isolated from Dioscorea rotundata Tubers

Studies were conducted in vitro to determine the antagonistic potential of Trichoderma harzianum for biological control of Fusarium moniliforme isolated from rotted Dioscorea rotundata tubers. The experiments were performed at Advanced Plant Pathology Laboratory, Federal University of Agriculture, Makurdi, Nigeria. Fungi organisms isolated and identified from the rotted white yam tubers were Botryodiploidia theobromae, Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus, Fusarium moniliforme, Fusarium oxysporum, Penicillium purpurogenum and Pestalotia sp. Pathogenicity tests done confirmed F. moniliforme as one of the organisms responsible for the rot in yam tubers in this location. The antagonist was introduced same time with the pathogen, two days before the inoculation of the pathogen and two days after the inoculation of the pathogen. Plates were incubated for 192 hours and measurements of mycelial radial growths were done at intervals of 24 hours beginning from the third day of inoculation. The results of in vitro dual culture interactions between T. harzianum and F. moniliforme showed that T. harzianum has potentials to significantly (P ≤ 0.05) inhibit the growth of F. moniliforme irrespective of the time of introduction of antagonist and duration of incubation. Mean Percentage growth inhibition was highest (58.70%) when the antagonist was introduced 2 days before inoculation of the pathogen, followed by (52.54%) introduction of the antagonist same time with the pathogen while the least percentage growth inhibition (34.33%) was recorded when T. harzianum was introduced 2 days after inoculation of F. moniliforme. Minimum inhibition concentration showed moderately effective to effective control depending on the time of introduction of the antagonist. In conclusion, biological control agents should be used since they are biodegradable, eco-friendly, less expensive and target specific. The introduction is done before the arrival of pathogenic organisms in order to achieve highest level of effectiveness in controlling post-harvest rots causing organisms.