Carduus nutans and Eryngium campestre - problem weeds found in permanent grassland of Băicoi, Prahova County.
The problem weed species, especially perennial, aggressive, potentially invasive ones, may cause various, large-scale and irrecoverable damages by reducing crop yields quantitatively and qualitatively, generating grasslands degradation, hindering maintenance works, rising production costs, producing toxic effects for both humans and livestock, as well as hosting, favoring and transmitting diseases and pests. The grassy flora of pastures consists, besides gramineous and leguminous fodder, of other species, of which some have a low forage value or provide a high level of toxiciy. The lack of efficient grassland management has led to the degradation of these lands by changing the optimum proportion of fodder species in the structure of the vegetal composition. In this context, the research and assessments conducted in the permanent grassland of Băicoi in Prahova County targeted the monitorization of vegetal cover species, identifying the problem weeds and determining the influence of the two species on the pastoral value. Two problem weeds have been identified: the Carduus nutans of the Asteraceae family and the Eryngium campestre of the Apiaceae family. The obtained results substantiated that the presence of the two weed species greatly reduced the pastoral value of the pasture from 94% (when Lolium perene, Trifolium repens and T. pratense predominated in the vegetal community composition) to 24%, as C. nutans and E. campestre showed a high degree of aggressiveness, prevented the development of valuable fodder species and endangered the useful pasture cover for animal feeding.