Disease Note.

First Report of Pseudomonas syringae pv. helianthi on Sunflower in Spain. J. M. Durán, ETSI Agrónomos, 28040 Madrid. E. Sobrino, CECOSA, Génova 9, 28004 Madrid, Spain. Plant Dis. 71:101. Accepted for publication 10 October 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0101D.

Diseased sunflower plants (Helianthus annuus L., inbred line CMS-HA-300, University of North Dakota) were detected in the CECOSA nursery (6,000 lines) in 1984. The symptoms -- white exudates on the leaf axils, brownish green lesions on the leaves, and light and dark brown lesions on both leaves and stalks -- were similar to those reported to be caused by Pseudomonas syringae pv. helianthi (Kawamura 1934) Young, Dye & Wilkie 1978. Bacteria isolated from lesions grew on Kado's selective medium D-4 and were fluorescent on King's medium B. When leaves of CMS-HA-300 were infiltrated with water suspensions of the bacteria, symptoms developed similar to those described. The bacteria were not pathogenic to bean (Phaseolus vulgaris L.). After 4 days of growth at 28 C, the bacteria were reisolated from inoculated sunflower leaves onto King's medium B. The bacteria were motile, gram-negative, obligately aerobic rods and were oxidase and arginine dihydrolase negative. On the basis of these characteristics and the symptoms, the pathogenic agent was identifed as P. s. pv. helianthi. This disease has been reported on sunflower in Japan and Canada but, as far as we know, has not been previously reported in Europe.