In recent years, the field of agriculture and the consumers have been paying much attention to discovering safe and quality foods produced with less or even without the use of synthetic phytopharmaceuticals. With a growing pressure of certain harmful organisms, however, food producers are faced with the problem of how to produce a sufficient amount of quality food free from pests and plant diseases. Over the years of searching for suitable solutions, plant strengtheners have become increasingly more prominent. The purpose of this research is to examine the efficacy of two commercial plant strengtheners. The research consists of studying their influence on certain pests, disease agents, beneficial organisms, and crops on two-row winter barley under field conditions. The experiment was conducted on the laboratory field of the Biotechnical Faculty, University of Ljubljana. In total, four treatments were carried out: Epin (1), in which the barley was treated with Epin ekstra, Cirkon and Siliplant preparations according to a specified spraying scheme; Plantonic (2), in which the barley was treated with the Plantonic preparation; Negative control (3), where the barley was not treated; and FFS (4), where the barley was treated with registered insecticides and fungicides. The examined plant strengtheners did not produce the anticipated effect on the cereal leaf beetle, aphids and barley leaf blotch, as well as on the quality and quantity of the crop, abundance and species representation of beneficial organisms. Most of the above categories did not reveal statistically significant differences between treatments due to the insufficient abundance of harmful or beneficial organisms. The tested plant strengtheners had a substantial impact on net blotch infection rates on barley up until phenophase BBCH 61. These agents offer an intriguing additional measure in protecting plants against pests and disease agents; however, they cannot be employed as complete substitutes for phytopharmaceutical products.