Summary The field experiments with spring barley cultivar KWS Olof were conducted in 2013–2014. The tested products (Cerone 480 SL), adjuvants (Slippa, Atpolan 80 EC) and fertilizers (ammonium sulfate, urea) and some of their mixtures were applied on spring barley at the stage of BBCH 35. The higher effectiveness of shortening stems of spring barley was obtained after the use of Cerone 480 SL at the dose of 0.75 l/ha as compared to the control. The reduction of spring barley stem length was dependent of spray liquid compounds and it was 9.7–13.0% (2013) and 2.6–11.0% (2014) in the years of investigation, respectively. The addition of adjuvants Slippa or ammonium sulfate to the spray liquid containing ethephon improved efficacy of grown retardants. The method of application of ethephon did not have any influence on yield of spring barley and some parameters of yield component. However the usage of full or reduced doses of ethephon caused a non-significant decrease the thousand grain weight compared to the untreated plots. In both years of the study no phytotoxicity effect of the examined mixture was observed on spring barley cultivar KWS Olof.