Bacterial canker caused by the bacterial pathogen Pseudomonas syringae is characterized by killed buds and stems. The disease can be severe when environmental conditions support growth and infection of tissues in the fall and spring. The disease is especially damaging to young succulent plants. Copper is sprayed onto plants to control the growth of the pathogen and the development of bacterial canker. P. syringae actually refers to a complex group of pathogens, with individual members that have either a wide host range or narrow host range. Surprisingly, little was known about P. syringae causing bacterial canker on blueberry. It was not known if only a single type of P. syringae with a narrow host range caused bacterial canker or if multiple types of the pathogen complex caused bacterial canker. P. syringae can use many traits to cause plant diseases, such as the production of plant toxins or the ability to nucleate ice formation.