Dynamics of weed infestation of main agricultural crops in Belarus

In Belarus about 300 weed plant species are marked, dominated by 30 – 40 species which are found on practically all the fields. Changes in the numbers of each weed species depend on many factors. The data of itinerary inspections of agricultural crops done in 1981 – 1985 and 1996 – 2003 show the specific composition change of the main dominating weed plants in comparison with 1939. The reasons promoting change of the specific composition of crop weed infestation are shown.