Biocontrol Potential of Trichoderma Harzianum against Rot Causing Fungi of White Yam (Dioscorea Rotundata Poir) Tubers (Published)
Biological control potential with Trichoderma harzianum in the control of postharvest fungal pathogens of Pepa white yam tubers in storage was carried out for two years. Rotted Ogoja and Pepa white yam tubers were collected from farmers’ barns in Zaki-Biam, Benue State, Nigeria. Pathogenicity tests conducted on healthy Pepa yam tuber cultivars after fourteen days of inoculation revealed that the tubers were susceptible to A. flavus, F. moniliforme and P. expansum. Treatments comprised either inoculation of yam tubers with A. flavus, F. moniliforme and P. expansum alone or paired with T. harzianum as well as a control where the tubers were neither inoculated with antagonist nor with fungi pathogens and were stored for five months between December, 2015 and April, 2016 and between December, 2016 and April, 2017. Results obtained in the first year of storage showed that tubers treated with fungi pathogens alone caused mean percentage rot of between 8.89 % (P. expansum) and 20.00 % (A. flavus) while those treated with T. harzianum alone produced only 2.22 %. In the paired treatments, mean percentage rots were between 4.44 % (P. expansum × T. harzianum) and 6.67 % (A. flavus × T. harzianum). The Findings in the second year revealed 13.33 % (P. expansum), 22.22 % (A. flavus) and 4.44 % (T. harzianum) in the alone treatments while paired treatments produced mean rot of between 4.44 % (P. expansum × T. harzianum) and 8.89 % (A. flavus × T. harzianum). The Results revealed that P. expansum was the most antagonized while A. flavus was the least inhibited. The findings revealed that T. harzianum (biological control agent) was more effective in inhibiting the growth of A. flavus, F. moniliforme and P. expansum in the first year of storage compared with the second year of storage. The antagonist therefore has biological potentials in controlling fungi pathogens of yam in storage.
Keywords: Aspergillus flavus; Biocontrol; Pathogenicity Test; Trichoderma harzianum; Zaki-Biam.