Potato (Solanum tuberosum) seed production is a critical element of the potato industry in Zimbabwe. Production in the potato industry is constrained by poor seed quality caused by the bacterial wilt pathogen Ralstonia solanacearum. The pathogen is known to be highly destructive in potatoes. R. solanacearum produces several virulence factors which invade the plant’s natural defense mechanism. Trichoderma species are well known for their antagonistic activity against several phytopathogens, including R. solanacearum. They restrict the growth of pathogens by a variety of means like parasitism and the release of antibiotic volatile and non-volatile metabolites. The study aimed to screen and evaluate the growth inhibition potential of Trichoderma strains against R. solanacearum. Potential strains of Trichoderma (NY, P3, CA, and C9) were isolated from the root samples of potatoes. NCBI blast searches of the four Trichoderma spp. identified them as Trichoderma asperellum, showing a 99% similarity with GeneBank strains. The inhibitory effect of the antagonists was evaluated in vitro using a Completely Randomized Design. The results showed considerable antagonistic potential for the biocontrol of R. solanacearum by all Trichoderma spp. T. asperellum (NY) was found to be highly inhibitory to R. solanacearum in dual culture, followed by T. asperellum (CA) and Trichoderma harzianum (T77); T. asperellum (C9) and T. asperellum (P3) showed least inhibitory effect on the growth of R. solanacearum. The pathogen was significantly (P < 0.05) inhibited by all the Trichoderma strains used in the study. The results from this study also show that Trichoderma can inhibit the growth of R. solanacearum in vitro. 

 

Key words: Trichoderma species, antagonistic, Ralstonia solancearum, phytopathogens, In-vitro.