Antagonistic Potential of Local Trichoderma viride and Trichoderma longibrachiatum Isolates Against Black Scurf Disease Caused by Rhizoctonia solani on Potato

Abstract

The present study was conducted in the laboratories of the Plant Protection Department at the Agricultural Research Center in Tripoli to evaluate the antagonistic efficiency of two local isolates of the biocontrol agent Trichoderma against Rhizoctonia solani, which causes black scurf disease on potato. The pathogenic fungus was isolated from infected potato tubers collected from the Bani Walid region. The dual culture technique was employed to assess the inhibitory potential of T. viride (T1) and T. longibrachiatum (T2). Statistical analysis using the SAS program and Duncan's multiple range test revealed significant differences between the treatments. The results demonstrated that the isolate T. longibrachiatum (T2) exhibited the highest inhibitory effect, reaching an inhibition rate of 97% against the pathogen R. solani. Meanwhile, the isolate T. viride (T1) achieved an inhibition rate of 88%. Microscopic examination of the interaction zones confirmed the occurrence of direct mycoparasitism. Both Trichoderma species showed a high ability to suppress the growth of the pathogen's mycelium by coiling around the hyphae of R. solani, leading to mycelial deformation and subsequent death. This study concludes that the local isolates of T. longibrachiatum and T. viride are highly effective biological control agents against black scurf disease under laboratory conditions. This effectiveness is attributed to the direct parasitic mechanism and the secretion of inhibitory compounds. The findings suggest that these isolates could serve as a sustainable alternative to chemical fungicides, reducing environmental hazards and preventing the development of resistant pathogen strains. The study recommends further genetic characterization of these isolates and evaluating their efficacy under field conditions.