In Vitro Assessments Potential of Trichoderma harzianum for Biological Control of Botryodiplodia theobromae on White Yam (Dioscorea rotundata Poir) Tuber

Abstract

The potential of Trichoderma harzianum as biocontrol agent of Botryodiplodia theobromae of white yam (Dioscorea rotundata) tuberrot was carried out at Advanced Plant Pathology Laboratory, Federal University of Agriculture, Makurdi, Nigeria. The antagonist was introduced at three different times (same time with the pathogen, 2 days before the inoculation of the pathogen and 2 days after the inoculation of the pathogen) on potato dextrose agar. The dual culture and control plates were incubated at ambient room temperature for 192 hours. Measurements of mycelial redial growths were done at 24 hours interval beginning from the 72 hour. In the dual culture tests, the mycelial growths of the pathogen were inhibited by the antagonist, while the control grew uninhibited. The mean percentage growth inhibition of mycelial of B. theobromae when inoculated same time with T. harzianumwas 48.38% compared with 70.19% inhibition when the antagonist was introduced 2 days after inoculation of the pathogen. The highest mean percentage growth inhibition of 70. 24% was recorded when the antagonist was introduced 2 days before the inoculation of the pathogen. The results revealed that T. harzianum was able to significantly (P ≤0.05) inhibit the growth of B. the obromae in culture at three different times of introduction of the antagonist. Minimum inhibition concentration (MIC) for the three treatments showed that T. harzianum was more effective in controlling B. theobromae when it was introduced 2 days before inoculation of the pathogen. It is therefore, concluded that in vitro control using T. harzianum is a good antagonist for biological control of B. theobromae causing dry rot in yam tubers.