Bacterial leaf rot of Odontioda orchids caused by Enterobacter cloacae.

An unknown disease causing leaf rot on leaves of Odontioda sp., which is an intergeneric hybrid of Odontoglossum, occurred in Tochigi Prefecture, Japan, during the summer of 1995. One species bacterium was almost purely isolated from the infected leaves. The isolated strains were pathogenic to Odontioda orchids in the dark with high temperature stress and high humidity. Based on results of API 20E strips and other physiological and biochemical tests, the strains were identified as Enterobacter cloacae (Jordan 1890) Hormaeche and Edwards 1960. They were also pathogenic to other orchids such as Calanthe discolor, C. furcata, Habenaria radiata, Miltonia sp. and Phaius minor f. punctaus, after inoculation and incubation for 2 days at 35°C. This is the first report of an orchid disease caused by E. cloacae, therefore, the name of “Bacterial leaf rot disease of Odontioda” was proposed.