Pathogenicity and identification of the lilac pathogen, Pseudomonas syringae pv. syringae van Hall 1902.
Comparative in planta studies with P. syringae pv. syringae established optimum conditions for disease expression in lilac in terms of inoculum concn, host age and post-inoculation conditions (temp. and day-length). Reproducible disease reactions required an inoculum concn exceeding the ED50, 5 × 106 c.f.u./ml, and a temp. for post-inoculation incubation not exceeding 19°C. A revised host range of P. syringae pv. syringae, proposed on the basis of confirmation of pathogenicity of strains to lilac, comprises 44 species of monocotyledonous and dicotyledonous plants. Nine new hosts Abelmoschus esculentus, Bromus willdenowii, Camellia sinensis, Centrosema pubescens, Citrullus lanatus, Cotoneaster sp., Cucumis melo, Populus × euramericana and Triticum aestivum, are recorded. A comparative lab. study was made of strains of P. syringae pv. syringae using >30 selected biochemical and nutritional tests. The pathovar could be characterised on the basis of 11 of these which may prove to be useful determinative tests.