In Rajasthan, bacterial stripe & black chaff disease of barley (Hordeum vulgare) caused by Xanthomonas campestris pv. translucens has become an upcoming and endemic disease in recent years. The bacterium was found to be seed-borne Seed to seedling transmission of the bacterium showed a quantitative relationship in the density of contaminated / infected seed. The pathway of the bacterium from germinating seed was observed emanating from the husk (glumes) and pericarp to coleoptile and above ground aerial plant parts. The bacterium was observed located in the intercellular spaces of parenchymatous cells with dissolution of cell walls leading to cavities full of bacterial masses which in turn converted stripes into blotches. Seed transmission studies indicated that infected seed is an important primary source of inoculum and recurrence of the disease from one season to next. Meteorological observations indicated that the temperature and relative humidity, played an important role in the initiation and development of the disease. In terms of epidemiology, the present barley production system in the area under study revealed that irrigation with overhead sprinklers favours the disease.