A three-year field experiment, carried out over 2001-2003, investigated the effect of cultivars and weed control methods on the weed infestation of pea (Pisum sativum L.) and on its yielding. The research involved low-, medium- and high-input growing technologies, including the mechanical and chemical weed control methods. The experiment involved four pea cultivars: two edible, general-use, cultivars: Rola and Agra and two fodder cultivars: Sokolik and Wiato. Analyzing the weed infestation and weed control methods and the competitiveness of cultivars towards weeds, it was found that the weed infestation had a priori a significant effect on yield components (plant density, number of pods per plant, seed weight per pod and 1000 seed weight), as well as on yielding of each cultivar researched. A negative effect of weed infestation was observed in all the research years, especially in the second year with the least favorable climatic conditions of the entire vegetation period, which concerned especially crops grown using the low-input technology which involved mechanical weed control. However the application of the chemical weed control facilitated a weed reduction and the competitiveness towards the plants of all the cultivars grown using the high-input technology, even under the least favorable climatic conditions of the vegetation period. The analysis of the reaction of cultivars to the degree of weed infestation revealed that Rola was the most competitive cultivar towards weeds, especially under extremely unfavorable conditions.

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