Identification and characterisation of viral and bacterial pathogens affecting ulmus laevis. Pathogens in Ulmus sp.

Scientific findings indicate thatviruses are widespread in trees of forests and urban green, and may cause losses of economic importance. Over many years a monitoring was carried out with over 100 years old European white elms(Ulmus laevis PALL.) in an urban park in eastern Germany. During the last years, they showed leaf symptoms such as chlorotic ringspots, necroses and dieback, suggesting a virus as causal agent. Fungal and bacterial pathogens as causal agent of these symptoms could be excluded by microbiological assays. Also an infection by well studied viruses such as Cherry leaf roll virus (CLRV), Elm mottle virus(EMV), Arabis mosaic virus(ArMV) and Tobacco ringspot virus(TRSV) could not be confirmed. However, some facts point to a member of the genus Carlavirus. The aim of the present study is the isolation and characterization of a putative viral pathogen which is so far unknown. Based upon the assumption that the causal agent belongs to the genus Carlavirus, we apply different specific molecular biological and biochemical methods to identify the putative virus.