Abstract: Many plant pathogens, especially Rhizoctonia solani, Pythium spp. and Alternaria spp. can seriously affect seedling growth and crop production. Trichoderma is recognized as a suitable biological plant protection product because of its capability to enhance the plant’s nutrient utilization, foster plant growth, and prevent plant pathogens. The aim of the study was to investigate the effects of Trichoderma on bean growth and the reduction of disease severity by forming experimental groups in pot application. The ability of Trichoderma strains to grow in different salinity ranges and their effects on germination success when applied to different seeds were also tested. In the study, Trichoderma harzianum ID11D (T. harzianum ID11D) alone and Trichoderma atroviride ID20G (T. atroviride ID20G) alone were applied to bean seedlings infected with R. solani. It was found that bean plants inoculated with pathogens in pots treated with T. harzianum ID11D had better data and biomass than the untreated control with Trichoderma inoculated with R. solani. In the pot experiment, it was found that the number of root hairs and the fresh and dry weights of roots increased and the disease effect decreased in the bean plant groups inoculated with the T. harzianum ID11D. Application of T. atroviride ID20G only of the pot group resulted in an increase in the wet and dry weight of the stem. Based on the results of our study, Trichoderma strains were found to have beneficial effects that may be of interest for the development of commercial products containing Trichoderma.