Detection of soluble antigens of Erwinia salicis in leaves of Salix alba by Enzyme‐linked Immunosorbent Assay

Soluble antigens of Erwinia salicis are transported through the xylem vessels to the leaves of Salix species. These antigens can be detected by the use of the Enzyme‐linked Immunosorbent Assay (ELISA) in willow trees in the absence of bacterial cells and are also produced in pure cultures. In this way populations of E. salicis occurring in stem or branches can be traced in the leaves. The possibilities for more general application in the detection of vascular parasites is discussed.