EN
The present study was carried out in the period 2007– 2009 in the Experimental Farm in Bezek near the city of Chełm. The aim of the investigation was to compare weed infestation of the husked (Krezus) and naked (Cacko) oat cultivars cultivated under conditions of different weed control treatments. The following weed control levels were compared: A – control object; B – harrowing twice; C – application of the herbicide Mustang 306 SE; D – herbicide Mustang 306 SE + foliar fertilizer Insol 3; E – herbicide Mustang 306 SE + two foliar fertilizers: Insol 3 and FoliCare 18:18:18. The husked oat cv. Krezus was more competitive against weeds. Number of dicotyledonous weeds and of monocotyledonous weeds, total weeds, and air-dry weight of above-ground parts of weeds in the crop of this cultivar were all significantly lower compared to the naked cv. Cacko. From the group of dicotyledonous species, Chenopodium album, Galinsoga parviflora, Matricaria maritima ssp. inodora, Polygonum aviculare, and Stellaria media were the dominant species in the crops of the oat varieties under investigation, whereas among the monocotyledonous species Echinochloa crus-galli, Setaria pumila, Apera spica-venti, and Elymus repens occurred in greatest numbers. The application of the herbicide Mustang 306 SE decreased the number of dicotyledonous weeds and air-dry weight of weeds, compared to the treatment in which mechanical weed control had been used.