In 2020 we designed a field experiment at the Biotechnical Faculty in Ljubljana, where we planted potato of the 'Natascha' variety. Before planting we soaked tubers and later sprayed the plants of potatoes three times with Rhizoflo Premium (RH), Bioamino-L (BL) and a product based on bacteria Bacillus amyloliquefaciens (BA). The RH contains rhizobacteria, the BL contains amino acids, and the BA an antagonistic bacterium. They are supposed to stimulate the plant's growth, development of resistance to stress, absorption of nutrients and affect the yield. The purpose of the experiment was to study the effect of products on the germination of potato, the occurrence of Colorado potato beetle (Leptinotarsa decemlineata), wireworms (Agriotes spp.), early blight of potato (Alternaria solani), late blight of potato (Phytophthora infestans), and on the yield of potato. On 1000 m2 large field we designed three blocks in which we conducted three repetitive experiments. In each block we had four treatments, within which we also applied phytopharmaceutical products in three different concentrations (100, 75 and 50% of the recommended dosage). We found significant differences in potato yield among products, while we did not confirm significant differences in the effect on the yield of potato among concentrations of phytopharmaceutical products. We also found out that the used products (RH, BL and BA) did not have an important impact on the occurrence of potato pests and diseases. The treatment with BL proved to be the best of them with an average yield of 26.88 t/ha, the lowest number of Colorado potato beetle occurrences, and the lowest number of holes per potato tuber due to wireworms. Product RP had the lowest effect on potato yield and the highest number of holes per tuber in the treatment with this preparation.