In 2005-2007 at the Education and Research Station Krasne (50^o03’ N; 22^o06’ E) near Rzeszów, on brown soil formed from loess classified as the good wheat complex, a study was carried out on the effect of cultivation methods on the weed infestation and yield of two-species mixtures with 50% of spring wheat, spring barley and oat. The mechanical and chemical method using harrowing and ½ dose of the herbicide Chwastox Trio 540 SL was characterized by the highest effectiveness in limiting the total number and mass of weeds, especially in the oat-barley mixture. Applying each method of cultivation resulted in a significant increase in the mixture grain yield as compared with the control treatment. Significantly lower grain yields were obtained on the treatments after the application of harrowing and the full dose of the herbicide as compared with the herbicide application at a smaller dose after earlier harrowing. The oat-barley mixture was characterized by a higher yield-forming potential. Its yield amounted to 4.42 t·ha^-1 and was significantly higher, on average by 0.45 t·ha^-1, than the yield of the other mixtures.

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