Abstract A description is provided for Pseudomonas phaseolicola . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Phaseolus vulgaris, P. coccineus, P. lunatus var. macrocarpus, P. multiflorus, Pueraria thunbergiana (9: 424). Also Glycine max on inoculation (32: 114). Phaseolus atropurpureus is recorded as a natural secondary host in Queensland (42: 298). DISEASE: Halo spot or halo blight. On seeds, pods (especially the sutures), leaves and stem, and also causing stem girdling or wilt. Frequently referred to as grease spot in Europe because of the dark green spots appearing on the pods. The symptoms of halo blight are very similar to common blight ( Xanthomonas phaseoli ; CMI Descripts. 46). Distinguishing signs are given by the exudate, when present, which is yellow in common blight and light cream or silver coloured in halo blight. In halo blight a single water-soaked spot may be at the centre of a halo-like zone 2.5 cm diam. Systemic infection often results in foliar mosaic and leaf malformation (35: 807). GEOGRAPHICAL DISTRIBUTION: Widespread and probably in most countries where dwarf beans are grown (CMI Map 85, Ed. 2 19S6). TRANSMISSION: On the surface of seed or between the seed coat and cotyledons. Also spread in the field by wind-driven rain splash which may carry inoculum as far as 85 ft. from a point source (43, 2141). Wounds are not a necessary prerequisite for infection which normally occurs through the stomata. The pathogen may be spread by overhead sprinkler irrigation in a late maturing crop in arid regions (34: 339), but not by furrow irrigation. Pseudomnas phaseolicola does not appear to survive the winter in soil or plant debris (26: 41, 373) but may overwinter in cankers of living kudzuvine ( Pueraria thunbergiana ) (7: 585).