Apical Chlorosis and Leaf Spot of Jerusalem Artichoke Incited by Pseudomonas syringae pv. tagetis. W. W. Shane, Research Fellow, Department of Plant Pathology, University of Minnesota, St. Paul 55108. J. S. Baumer, Assistant Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 68:257-260. Accepted for publication 21 November 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-257.

Pseudomonas syringae pv. tagetis causes apical chlorosis, chlorotic and necrotic leaf spots, and stunting of Jerusalem artichoke (JA) plants in Minnesota. More than 80% of the plants in several fields had disease symptoms in 1983. Reduced stands resulted from eventual necrosis and death of many plants that emerged chlorotic. Bacterial strains caused either necrotic spots with slight halos or necrotic spots and chlorosis upon spray inoculation or infiltration of JA. Strains that induced chlorosis were indistinguishable from known strains isolated from sunflower, marigold, or ragweed in pathogenicity on JA, sunflower, marigold, and zinnia, and in biochemical tests. The bacterium is tuberborne.