Disease Note.

Bacterial Leaf Spot and Blight of Sunflower Caused by Pseudomonas syringae pv. helianthi in Yugoslavia. M. Arsenijevic, Faculty of Agriculture, 21000 Novi Sad, Yugoslavia. S. Masirevic, Faculty of Agriculture, 21000 Novi Sad, Yugoslavia. Plant Dis. 73:368. Accepted for publication 27 December 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0368A.

In 1987, small pale-green, water-soaked spots were observed on leaves of several I-mo-old sunflower hybrids (Helianthus annuus L.) in Vojvodina, Yugoslavia. The spots enlarged and coalesced, forming irregular necrotic areas. A bacterium consistently isolated from these lesions formed large white, glistening colonies on nutrient agar + 5% sucrose and a water-soluble, green fluorescent pigment on King's medium B. The bacterium was a gram-negative rod, oxidase-negative, able to induce a hypersensitive reaction in tobacco, negative for soft rot of potato, indole- and arginine dihydrolase-negative, levan- and catalase-positive, and not pathogenic to peach shoots. Koch's postulates were completed by spraying a bacterial suspension on sunflower plants in the greenhouse. The bacterium was identified as Pseudomonas syringae pv. helianthi (Kawamura) Young, Dye & Wilkie. Symptoms produced by this bacterium are totally unlike the apical chlorosis produced by P. s. pv. tagetis (Hellmers) Young, Dye & Wilkie. This is the first report of P. s. pv. helianthiin Yugoslavia and the second report of it in Europe.