Bromus secalinus (Poaceae) - a vanishing or a widespread weed species of cereal crops in north-eastern Poland?
Bromus secalinus L. is a common weed of winter cereal crops. At the end of the 20th century, B. secalinus was considered disappearing or vanishing in Poland, including in north-eastern regions, by many authors. B. secalinus has been listed as vulnerable in Poland in the latest update of the Polish "red list" (Zarzycki & Szeląg 2006). The field investigations carried out by the authors of this study in 2007-2010 in winter cereal crops in the Sępopol Plain and in the Suwałki Landscape Park (NE Poland) indicate that the occurrence of Bromus secalinus has increased in the studied area. A comparison of recent findings with 20th c. data revealed a considerable increase in both the abundance of B. secalinus and the number of infested fields, thus pointing to the expansive character of the analyzed species in north-eastern Poland. In 2007-2010, Bromus secalinus was encountered most frequently in winter wheat. The species was much less common in triticale fields, and relatively rare in the other winter cereals. The species showed a preference for fertile soils of good wheat complex and very good rye complex. The majority of the studied phytocoenoses were characterized by low weed infestation (+ and 1 on the Braun-Blanquet scale). However, in several fields the predominant species (abundance of 4 and 5) was B. secalinus and not the cultivated crop.