Xtt is disseminated as a seed-borne bacterial pathogen that causes leaf streak diseases in wheat and other cereals. It has a widespread distribution around the world. Grain yield losses arising from infection are very variable but significant losses can occur, especially when environmental conditions are favourable for disease development. Seed dissemination is inefficient compared with other pathogens and local disease spread on farms is slow, which limits Xtt impacts. However, in parts of northern US, Xtt epidemics have occurred recently and are a cause for concern.