This is less common than botrytis blight but can be more devastating. Black leathery spots fist occur on the buds. Control measures recommended for botrytis blight should be followed. Leaf blotch is a disease that usually occurs after flowering. Destroy affected foliage as it occurs and all foliage after a killing frost.
Mosaic virus produces yellowish blotches and rings on the foliage.
Infected plants are not dwarfed or deformed. Destroy infected plants to prevent spread. Very little direct damage results from their feeding.