While bacterial spot is more common on susceptible varieties grown in coastal areas, it is also becoming a problem in inland production areas.
Wet conditions between blossom and petal fall favours both leaf and fruit infection on peaches and nectarines.
Windy, wet conditions and heavy dews during the growing season will also favour secondary infections.
Exposed blocks are more vulnerable.
Trees under nutrient stress or stress from other pests and diseases are more likely to be infected by bacterial spot.
Maintain high soil fertility and a good pest management program.
Destroy nearby feral or neglected prunus as they can act as a reservoir for the disease.
Do not prune during wet weather.
See this article in Tree Fruit August 2019