Internal Decay of Onions Caused by Enterobacter cloacae. A. L. Bishop, Associate Plant Pathologist, California Department of Food and Agriculture, Analysis and Identification Branch, Sacramento 95814. R. M. Davis, Extension Specialist, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 74:692-694. Accepted for publication 6 February 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0692.

Enterobacter cloacae was consistently isolated from diseased onions (Allium cepa) collected from several fields of mature plants in California’s San Joaquin Valley following a period of extreme heat (air temperatures 40–45 C). Several of the innermost leaf bases of affected bulbs were discolored (brown to black) and flaccid. All nine strains of E. cloacae tested, including those isolated from onions and other plant species and the type strain, reproduced these symptoms in inoculated onion bulbs incubated at 37 C; disease was less pronounced at 22 C. Enterobacter cloacae did not cause disease in young, growing onions.