The assessment of the diversity of weed flora communities in crops cultivated in selected organic farms in Lublin province.

The aim of the study was analysis of weed flora communities accompanying crops cultivated in 5 selected organic farms, located near Pulawy (Lublin province). The research was carried out in the second decade of July 2011 and included an assessment of species composition, abundance and dry matter of weeds in 3 groups of crops: cereals, legumes or their mixtures with grasses and root crops (or berries). Diversity of weed communities in farms were from 29 to 37 species. Average number of weeds was 165 plants · m and weed dry matter 71 g·m. The most infested crops were cereals (233 szt.·m and 83 g·m). In root crops dry matter of weeds only in one farm was significant, more than 100 g·m. Small legumes and their mixtures with grasses and grain legumes were distinguished by the smallest weed infestation. In most of the tested farms weed control was done properly, and a large number of weeds was due to second infestation by Echinochloa crus-galli and Setaria viridis. There was a large variety of species, fulfilling important functions in agroecosystems as animal feed, a source of nectar, habitat for beneficial and rare organisms.