Abstract
In the organic bean crops (Phaseolus vulgaris) grown in open cultivation during the vegetation period of 2012, 14 weed species were found in the villages Ljutovo and Orom. The percentage of invasive species was 28.57%. Ambrosia artemisiifolia was characterized as highly invasive, Sorghum halepense as sporadically invasive, and Amaranthus retroflexus and Datura stramonium as potentially invasive species. Low diversity and low density of weed flora in organic bean crops are the factors causing a high percentage of invasive species in the floristic composition, so monitoring of these species is necessary. The weed flora dominated by therophytes (71.43%), the dominance of weed-ruderal plants (64.29%), and the presence of widespread taxa in the bean crops indicate strong anthropogenic influence and instability of the weed flora. The largest number of the weed species bloom from June to August (71.43%). According to the ecological analysis of the weed flora, the studied agroecosystems were characterized as moderately arid (F-2.36), neutral to weakly alkaline (R-3.07), eutrophic-mesotrophic (N-3.71), well-aerated (D-3.64), non-saline (S-, 78.57%) with medium humus content (H-2.86), favorable light (L-3.86) and temperature (T-4.14) regime, and with temperate continental climatic conditions (K-2.93). Correlation analysis showed that invasive weed species began to bloom later and favored well-aerated and warmer habitats compared to other weeds. PCA analysis singled out habitat aeration and salinity as the main factors separating weeds in organic bean crops.