Biological Control Using Trichoderma harzianum against Penicillium purpurogenum, Causal Agent of White Yam Tuber (Dioscorea rotundata Poir) Rb

In vitro assessment of biological control of Trichoderma harzianum against Penicillium purpurogenum isolated from rotted yam tubers (Dioscorea rotundata Poir) in storage was conducted in the Advanced Plant Pathology Laboratory, Federal University of Agriculture, Makurdi, Nigeria. The antagonist and the pathogen were paired in dual culture at different times (antagonist same time with the pathogen, 2 days before the inoculation of the pathogen and 2 days after the inoculation of the pathogen). The inhibitory effect on the growing mycelial of the pathogen on potato dextrose agar (PDA) was measured for a period of 192 hours. Measurement of mycelia radial growth and the percentage growth inhibition (PGI) were done starting from the 72nd hour after incubation. The results of the interactions of the dual culture method showed that both the antagonist and the pathogen mycelial increased with increase in incubation period. Mean percentage growth inhibition (PGI) also increased with the highest inhibition of 69.01% recorded as a result of introducing the biological control agent two days before inoculation of P. purpurogenum (2dbipath). The next was by introduction of the bioagent same time with the pathogenic organism (Th×Path) with mean of 38.57%. The least average inhibition of 22.79% was recorded as a result of introducing the bioagent two days after the inoculation of the pathogen (2daipath). Result of the dual culture method between T. harzianum and P. purpurogenum differed significantly (P ≤ 0.05) at the different times of assessment. The minimum inhibition concentration (MIC) of T. harzianum that was introduced two days before the inoculation of P. purpurogenum was the most effective and was therefore considered best for biological management of white yam tuber fungi isolated from rotted yam in storage.