The purpose. To justify an opportunity of application of adjusters of growth of plants (AGP) on the basis of humic acids, biologically active substances and complex microfertilizer KompleMet against diseases of plants of a cucumber. Methods. Laboratory — study of effect of AGP on development of the causal organism of root rots secreted from plants of cucumber — fungus Fusarium solani App. et Wr. in crop in vitro (according to V.I. Bilay, 1982). Field experiments on determination of efficiency of AGP were led according to S.A. Tribel’s technique (2001). Results. It is established that fungus Fusarium solani App. et Wr. is the most susceptible to AGP on the basis of biologically active substances: Epin extra, salicylic and amber acids. Their inhibiting effect on the 3rd day had made 36,7; 56,7, and 33,3% accordingly. Integrated data of field probes confirmed that the highest efficiency against root rots had the alternative with application of microfertilizer KompleMet (K1+M1) — 60%. Efficiency of AGP on the basis of biologically active substances was below and made 55–52%. Efficiency of humic specimen Vympel Maxi was at the same level — 56%. Treatment of plants with AGP promoted lowering of the level of strikeness of plants of a cucumber with false mildew. Due to activation of growth processes at plants and presence of antifungal activity against causal organisms of diseases introduction in technique of growing of plants of cucumber of AGP made active reward payment of the crop. The increase of productivity had made 1,06–2,50 kg/m2. Conclusions. AGP on the basis of biologically active substances (Epin extra, salicylic and amber acids) essentially suppress growth of fungus Fusarium solani App. et Wr. in crop in vitro. AGP on the basis of humic substances and complex microfertilizer KompleMet (K1+M1) did not manifest stopping power activity. So, to increase efficiency it is necessary to search an opportunity of specimens to promote activation of nonspecific protective responses in plants. In sowings of a cucumber in film hothouses it is expedient in order to lower intensity of root rots to apply complex microfertilizer KompleMet (K1+K2) in dose of 1 l/hectare or one of AGP: on the basis of biologically active substances — salicylic acid (0,1 kg/hectare) or Epin extra (0,08 l/hectares); on the basis of humic substances — Vympel Maxi (1 l/hectare). Application of AGP in technique of growing of a cucumber ensures increase of productivity on 1,06-2,50 kg/m2.