The bacteria overwinters in dead plant material, but does not survive for long in water or soil. Bacteria are weak pathogens and need a natural opening (stomates and lenticels) or an injury (mechanical, insect or another disease) to infect.
Never work on plants or in the garden while plants are wet since the "bruising" and other mechanical injury helps to spread diseases. Bacteria are not controlled with fungicides. There are no bactericides available to gardeners that control these bacteria. Sanitation is the main control for these leaf spots.