Internal Decay of Onions Caused by Enterobacter cloacae

Abstract

Enterobacter cloacae was consistently isolated from diseased onions collected from several fields of mature plants in California's San Joaquin Valley following a period of extreme heat (air temperature 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