EVALUATION OF Trichoderma SPECIES’ ABILITY TO SUPPRESS Rhizopus stolonifer

Abstract

The present study was aimed at evaluating the in vitro abilities of isolated Trichoderma species from soil to control Rhizopus soft rot that occurred on sweet potato (Ipomoea batatas (L). Rhizopus stolonifer was isolated from infected sweet potato. The results of direct confrontation (in vitro) of the three isolated Trichoderma species (T. reseei, T. harzianum and T. koningii) against R. stolonifer on PDA medium, showed high inhibition in the mycelial growth of R. stolonifer. All these with individual variability displayed the best antagonistic potential where the maximum inhibition percentage observed was 87.50% for T. reseei which indicate an effective reduction in the mycelial growth of Rhizopus stolonifer after 3 days. The other two isolates were also able to inhibit the growth of the pathogen up to 77.80% and 66.70% for T. harzianum and T. koningii respectively. T. koningii showed the least inhibitory effect on the pathogen. Antagonism between the potential antagonists and pathogen indicated that the pathogen stops growing upon contact with the antagonist which continues its growth over the fungus colony. Observations on the growth and colonization of the test pathogen in dual culture screening by the antagonistic isolates suggest that different species of Trichoderma have variation in their ability to inhibit the growth of the pathogen and hence their possible use as biocontrol agents.