Infection of Cricket Bat Willow (Salix alba var. caerulea) Sm. by Erwinia salicis (Day) Chester detected in the Field by the Use of a Specific Antiserum

Abstract

SUMMARYThe use of a slide agglutination test on squeezed‐out sap of cultivated cricket bat willow trees allowed rapid diagnosis of infection by Erwinia salicis in the field. By this means, infection of “classically” diseased willow trees with both red leaf and wood staining was confirmed. Trees with either red leaf or wood stain, but not both symptoms, were also shown to be infected. Symptomless infection of cricket bat willow trees was detected. E. salicis was viable in the stumps of trees felled five years previously. Some of these stumps were in an advanced state of decay and some were producing symptomless leafy shoots. Trees dying with severe die‐back symptoms and infected with Armil‐ laria mellea, were shown to be infected with E. salicis. Salix caprea and S. vitellina, two wild species of willow, were also shown to be infected.