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Summary. Morphological, cultural and biochemical properties of 35 isolates of rod shaped Gram negative, yellow pigmented anaerogenic, fermentative bacteria were compared. The isolates comprised named cultures of Bacterium herbicola, Erwinia lathyri, E. ananas, E. milletiae, E. uredovora and B. typhi flavum, as well as organisms isolated from deer and man which were considered to be related to E. milletiae. The results showed that the organisms were indistinguishable from one another on the basis of the tests employed, and it is concluded that B. herbicola, B. typhi flavum, E. lathyri and E. ananas should be classified as Erwinia herbicola (Düggeli) Dye. Since there was insufficient information regarding the plant pathogenicity of E. milletiae and E. uredovora, it is suggested that they should remain separate species at present. The relationship of this group of organisms to certain coliforms and to flavobacteria is briefly discussed.

An anaerobic liquid enrichment method followed by plating on a selective medium revealed that the soft rot coliform bacterium Erwinia carotovora subsp. carotovora was generally present in water from drains, ditches, streams, rivers and lakes (including reservoirs) in southern Scotland and in Colorado, United States, in mountainous, upland and arable areas through the year. Many sites were remote from susceptible or diseased crops. Erwinia carotovora subsp. atroseptica was isolated much less frequently and no Erwinia bacteria were isolated from underground waters. Erwinia bacteria were also found in rain‐water in Scotland, in winter snow from mountain passes in Colorado, and in sea water from the west and east coasts of Scotland and from the coasts of Oregon, California, Texas, Louisiana and Florida. The significance of the occurrence of these bacteria in water is discussed in relation to the control of blackleg and soft rot diseases of potato by production of Erwinia‐free stocks.