Lactuca serriola L. presence on the set-aside soil

The possibility of Lactuca serriola L. infestation of sown stands of Bromus catharticus Vahl., Arrhenatherum elatius IL.) P. Beauv. ex J.S. et K.B. Pr esl, Festuca pratensis Huds., Dactylis aschersoniana Graebn., Tuifolium rep ens L., Medicago lupulina L., Lotus corniculatus L., Medicago media Pers. a nd fallow under different management at setting the soil aside (3 times cut during vegetation with removing of the mass, 2 times mulching during veget ation, once mulching in the end of vegetation and once cut in the end of ve getation with removing of the mass). Height, number of dry mass yield of La ctuca serriola L, were measured. Lactuca serriola L. infested especially le gumes stands harvested once in the end of vegetation period. Its share in t he total dry mass yield of a year reached in average 16% in the stands of M edicago lupulina L. and 36% in Trifolium repens L. stands. Grass stands wer e relatively little infested or nor at all. Lactuca serriola L. presence in the stands was influenced especially by the sown species. The infestation by Lactuca serriola L. was not significantly influenced by the stand manage ment. Multiple harvest of the stands during the vegetation (3 times cut, 2 limes mulching) prevented seeds creating and ripening of that species. The weed infestation in the year 1999 was significantly higher in comparison wi th the year 1997.