The spore over winters on infected leaves and canes. The real cause of this problem is dead soil over fertilized with chemicals.
Water containing chemicals kill the microorganisms found in the soil.
These are needed for proper assimilation of nutrients found in the soil and to control any fungus which may be found in the soil. Agri-Gro or any other natural liquid seaweed, bacterial mixture. Then add enough clean rain, or filtered water to make a gallon. Spray on leaves in afternoon. Spray as needed.