The influence of three methods of soil cultivation and two levels of mineral fertilisation on weed infestation of spring wheat canopy are presented in the paper. Methods of tillage: A – fall ploughing to 18-20 cm, B – cultivating (10-12 cm), C – harrowing (8-10 cm). Fertilisation levels: a – 117.3 kg NPK ha–1, b – 175.9 kg NPK ha–1. Spring wheat was planted in a four-field rotation: potato – spring wheat – seed beans – winter wheat. Weeds were controlled by herbicides: Puma Universal (69 g phenoxaprop-P-etyl + 75 g mefenpyr-dietyl ha–1) and Aminopielik D (1252.5 g 2.4 – D + 97.5 g dikamba ha–1). Apera spica–venti, Galinsoga ciliata, Galium aparine, Viola arvensis, Stellaraia media and Agropyron repens were the most abundant weed species. Increase of fertilisation level (b) diminished individual density of a majority of weed species. Reduced tillage methods caused significant increase in weed number in spring wheat canopy in comparison to typical tillage. Fertilisation level b slightly decreased the weed number. Fertilisation level b only slightly increased the weed air dry weight.