Abstract A description is provided for Xanthomonas vasculorum . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Saccharum officinarum . Also found naturally infecting Zea mays, Dictyosperma album, Thysanolaena maxima, Roystonea regia and Areca catechu . In addition to these, infection has beer; obtained after artificial inoculation on Bambusa vulgaris, Brachiaria mutica, Cocos nucifera, Coix lachyrma-jobi, Panicum maximum, Pennisetum purpureum, Sorghum halepense, S. verticilliflorum , 20: 381, S. vulgare, S. vulgare var. sudanense, Sorghum spp. (18, 710; 20, 381; 43, 218). DISEASE: Gumming disease or gummosis of sugarcane. On leaves, yellowish chlorotic stripes occur. These may be the only symptoms on the more resistant varieties. On other varieties they may become spotted with brownish spots that become necrotic with age. The necrosis may involve large areas of leaf. The vascular tissue of the stem becomes darkened and contains bacterial slime. In very susceptible varieties the yellow slime may also form below the terminal bud and sometimes interferes with the development of the top of the plant. The tops often die and the terminal bud decays. GEOGRAPHICAL DISTRIBUTION: Recently reported in the following countries: Africa: Ghana, Madeira, Malagasy Republic, Malawi, Mauritius, Mozambique, Reunion, Rhodesia, South Africa; North America: Mexico; Central & South America: Puerto Rico, Argentina, Brazil, Colombia, French Guiana, Far East: New Guinea; Hughes (34, 487) considers that the pathogen may not be present in New Guinea (CMI Map 3, ed. 5, 1971). The disease has been observed in the past in 25 or more countries where sugarcane is grown (48, 3137k; 50, 915y). In some it is claimed to have been eradicated and in others it has not been seen for many years. It may be that the local conditions and use of resistant varieties have combined to eradicate the pathogen. TRANSMISSION: Introduction into new areas and countries is by planting diseased setts or cuttings. Healthy setts may be infected from diseased ones during planting by means of the cutting knife. Agricultural tools, workers, vehicles, animals and even insects may carry inoculum from field to field. The most rapid and important local spread, however, is from plant to plant by wind-driven rain. Fresh wounds are needed for entry of the pathogen, but these are available, especially in windy weather, as a result of leaves rubbing together. The saw-tooth edges of the leaves cause many tiny abrasions (North, 1935; Hughes, 1961).