Effect of <i>Trichoderma</i> sp. on microbial rot of yam-tubers

Abstract

The effect of Trichoderma sp. on the rot of yam tuber by B theobromae, A niger and P oxalicum was investigated by inoculating Trichoderma sp. with the individual pathogens either simultaneously or with advanced inoculation of a pathogen using white yams (Discorea rotundata) obtained from Ondo State or Edo State. The result shows that inoculation of Trichoderma sp. simultaneously or not more than one day after prior inoculation of a pathogen, decreased rot incited by B theobromae, A niger or P oxalicum. However, whereas the reduction of rot caused by A niger or B theobromae in Ondo yam was statistically insignificant (p 0.05), that caused by P oxalicum in Edo yam (55.7 mm, control; 25.7 mm simultaneously; 26.3 mm, one day later) was statistically significant (p 0.05). Edo
State yam were rotted faster (51.5 mm) than the Ondo State yams (25.0 mm) suggesting the cultivars of white yams varying level of susceptibility to rot pathogen. A Trichoderma sp. isolated from yam tuber surface inhibited mycelia extention growth of B theobromae (52.5 %), A niger (17.8 %) and P oxalicum (42.5 %) in vitro indicating its potentials as a biocontrol agent of post harvest rot of yams.

Keywords:  Trichoderma sp., Yam-tubers, Pathogen, Mycelia, Antagonism