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Identification, Symptomatology, and Epidemiology of Fire Blight on Le Conte Pear in the Nile Delta of Egypt. T. Van Der Zwet, Research Plant Pathologist, USDA, Appalachian Fruit Research Station, Kearneysville, WV 25430. Plant Dis. 70:230-234. Accepted for publication 12 August 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-230.

Outbreaks of fire blight caused by Erwinia amylovora on Le Conte pear, the first in Egypt since 1962, were associated with heavy rainfall during bloom in 1982, rainfall combined with wind storms during bloom in 1983, and one 2-day rain during bloom in 1984. The severe occurrence of the disease, expressed mainly as blossom blight, caused a loss of blossoms varying from 10 to 75% per tree. Of 24 bacterial isolates from blighted pear tissues tested for colony morphology, pathogenicity, and fatty-acid composition, 22 were E. amylovora. Two isolates were identified as Pseudomonas syringae. On Bartlett seedling shoots, Egyptian isolates of E. amylovora generally appeared more virulent than two standard American cultures used for comparison. However, fatty-acid profiles of the Egyptian isolates matched those of the standard cultures in the E. amylovora library.