Disease Note.

First Appearance of Fire Blight, Caused by Erwinia amylovora, on Quince and Pear in Yugoslavia. M. Arsenijevi?, Faculty of Agriculture, 21000 Novi Sad and Zemun, Yugoslavia. M. Pani?, Faculty of Agriculture, 21000 Novi Sad and Zemun, Yugoslavia. Plant Dis. 76:1283. Accepted for publication 17 January 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-1283D.

Symptoms of fire blight were first observed on pears (Pyrus communis L.) in Macedonia in late 1989, and in 1990 a severe epidemic developed in pears and quince (Cydonia oblonga Mill.) for the first time in many parts of Yugoslavia. Pear trees (58 hal were uprooted in Bosanska Gradiska; quince trees (28 hal in Kavadarci and pear trees (26 ha) in Radovis, Macedonia; and quince trees (1.3 ha) and individual pear trees in Sabac, Serbia. A number of white bacterial colonies were isolated from lesions on diseased trees; the bacteria were rod-shaped, gram-negative, and motile with peritrichous flagella. All strains induced a hypersensitive reaction in tobacco and pelargonium leaves, necrotic areas on inoculated green pear fruit, and fire blight symptoms on quince and pear shoots. A milky white bacterial exudate developed on necrotic tissue of inoculated green pear fruit. Strains were positive for levan and catalase production and for gelatin liquefaction and negative for oxidase, starch hydrolysis, indole, and H2S production from peptone. The strains also reacted positively in slide agglutination tests with an antiserum produced from an authentic strain of Erwinia amylovora (Burrill) Winslow et al. The bacterium was identified as E. amylovora and is a new pathogen of pomaceous trees in Yugoslavia.